import java.util.*;
import java.util.zip.*;
import java.util.List;
import java.util.regex.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import java.util.concurrent.locks.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.table.*;
import java.io.*;
import java.net.*;
import java.lang.reflect.*;
import java.lang.ref.*;
import java.lang.management.*;
import java.security.*;
import java.security.spec.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.imageio.*;
import java.math.*;
class main {


static String snippetID1 = "#636", snippetID2 = "#747", diff;
static int contextSize = 1;

public static void main(final String[] args) throws Exception {
  if (args.length == 2) {
    snippetID1 = args[0];
    snippetID2 = args[1];
  }
  diff = unidiff(loadSnippet(snippetID1), loadSnippet(snippetID2));
  print(diff);
}


static String unidiff(String a, String b) {
  int contextSize = 1;
  return fromLines(BlockDiffer.generateUniDiff(toLines(a), toLines(b), contextSize));
}
static volatile StringBuffer local_log = new StringBuffer(); // not redirected
static volatile StringBuffer print_log = local_log; // might be redirected, e.g. to main bot

// in bytes - will cut to half that
static volatile int print_log_max = 1024*1024;
static volatile int local_log_max = 100*1024;
//static int print_maxLineLength = 0; // 0 = unset

static boolean print_silent; // total mute if set

static Object print_byThread_lock = new Object();
static volatile ThreadLocal<F1<String, Boolean>> print_byThread; // special handling by thread

static void print() {
  print("");
}

// slightly overblown signature to return original object...
static <A> A print(A o) {
  ping();
  if (print_silent) return o;
  String s = String.valueOf(o) + "\n";
  print_noNewLine(s);
  return o;
}

static void print_noNewLine(String s) {
  if (print_byThread != null) {
    F1<String, Boolean> f = print_byThread.get();
    if (f != null)
      if (isFalse(f.get(s))) return;
  }

  print_raw(s);
}

static void print_raw(String s) {
  s = fixNewLines(s);
  // TODO if (print_maxLineLength != 0)
  StringBuffer loc = local_log;
  StringBuffer buf = print_log;
  int loc_max = print_log_max;
  if (buf != loc && buf != null) {
    print_append(buf, s, print_log_max);
    loc_max = local_log_max;
  }
  if (loc != null) 
    print_append(loc, s, loc_max);
  System.out.print(s);
}

static void print(long l) {
  print(String.valueOf(l));
}

static void print(char c) {
  print(String.valueOf(c));
}

static void print_append(StringBuffer buf, String s, int max) {
  synchronized(buf) {
    buf.append(s);
    max /= 2;
    if (buf.length() > max) try {
      int newLength = max/2;
      int ofs = buf.length()-newLength;
      String newString = buf.substring(ofs);
      buf.setLength(0);
      buf.append("[...] ").append(newString);
    } catch (Exception e) {
      buf.setLength(0);
    }
  }
}
static Map<Thread, Boolean> _registerThread_threads = synchroMap(new WeakHashMap());

static Thread _registerThread(Thread t) {
  _registerThread_threads.put(t, true);
  return t;
}
static boolean preferCached = false;
static boolean loadSnippet_debug = false;

public static String loadSnippet(String snippetID) {
  try {
    return loadSnippet(parseSnippetID(snippetID), preferCached);
  } catch (IOException e) {
    throw new RuntimeException(e);
  }
}

public static String loadSnippet(String snippetID, boolean preferCached) throws IOException {
  return loadSnippet(parseSnippetID(snippetID), preferCached);
}

public static String loadSnippet(long snippetID) {
  try {
    return loadSnippet(snippetID, preferCached);
  } catch (IOException e) {
    throw new RuntimeException(e);
  }
}

public static String loadSnippet(long snippetID, boolean preferCached) throws IOException {
  String text;
  
  // boss bot disabled for now for shorter transpilations
  
  /*text = getSnippetFromBossBot(snippetID);
  if (text != null) return text;*/
  
  initSnippetCache();
  text = DiskSnippetCache_get(snippetID);
  
  if (preferCached && text != null)
    return text;
  
  try {
    if (loadSnippet_debug && text != null) System.err.println("md5: " + md5(text));
    String url = "http://tinybrain.de:8080/getraw.php?id=" + snippetID + "&utf8=1";
    if (nempty(text)) url += "&md5=" + md5(text);
    String text2 = loadPage(url + standardCredentials());
    boolean same = eq(text2, "==*#*==");
    if (loadSnippet_debug) print("loadSnippet: same=" + same);
    if (!same) text = text2;
  } catch (RuntimeException e) {
    e.printStackTrace();
    throw new IOException("Snippet #" + snippetID + " not found or not public");
  }

  try {
    initSnippetCache();
    DiskSnippetCache_put(snippetID, text);
  } catch (IOException e) {
    System.err.println("Minor warning: Couldn't save snippet to cache ("  + DiskSnippetCache_getDir() + ")");
  }

  return text;
}

static File DiskSnippetCache_dir;

public static void initDiskSnippetCache(File dir) {
  DiskSnippetCache_dir = dir;
  dir.mkdirs();
}

public static synchronized String DiskSnippetCache_get(long snippetID) throws IOException {
  return loadTextFile(DiskSnippetCache_getFile(snippetID).getPath(), null);
}

private static File DiskSnippetCache_getFile(long snippetID) {
  return new File(DiskSnippetCache_dir, "" + snippetID);
}

public static synchronized void DiskSnippetCache_put(long snippetID, String snippet) throws IOException {
  saveTextFile(DiskSnippetCache_getFile(snippetID).getPath(), snippet);
}

public static File DiskSnippetCache_getDir() {
  return DiskSnippetCache_dir;
}

public static void initSnippetCache() {
  if (DiskSnippetCache_dir == null)
    initDiskSnippetCache(getGlobalCache());
}



static String fixNewLines(String s) {
  return s.replace("\r\n", "\n").replace("\r", "\n");
}
static Map synchroMap() {
  return synchroHashMap();
}

static <A, B> Map<A, B> synchroMap(Map<A, B> map) {
  return Collections.synchronizedMap(map);
}
  public static String loadTextFile(String fileName) {
    return loadTextFile(fileName, null);
  }
  
  public static String loadTextFile(String fileName, String defaultContents) {
    try {
      if (!new File(fileName).exists())
        return defaultContents;
  
      FileInputStream fileInputStream = new FileInputStream(fileName);
      InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "UTF-8");
      return loadTextFile(inputStreamReader);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }
  
  public static String loadTextFile(File fileName) {
    return loadTextFile(fileName, null);
  }

  public static String loadTextFile(File f, String defaultContents) {
    return f == null ? defaultContents : loadTextFile(f.getPath(), defaultContents);
  }
  
  public static String loadTextFile(Reader reader) throws IOException {
    StringBuilder builder = new StringBuilder();
    try {
      char[] buffer = new char[1024];
      int n;
      while (-1 != (n = reader.read(buffer)))
        builder.append(buffer, 0, n);
        
    } finally {
      reader.close();
    }
    return builder.toString();
  }
static volatile boolean ping_pauseAll;
static int ping_sleep = 100; // poll pauseAll flag every 100
static volatile boolean ping_anyActions;
static Map<Thread, Object> ping_actions = synchroMap(new WeakHashMap());

// always returns true
static boolean ping() {
  if (ping_pauseAll || ping_anyActions) ping_impl();
  return true;
}

// returns true when it slept
static boolean ping_impl() { try {
  if (ping_pauseAll && !isAWTThread()) {
    do
      Thread.sleep(ping_sleep);
    while (ping_pauseAll);
    return true;
  }
  
  if (ping_anyActions) {
    Object action;
    synchronized(mc()) {
      action = ping_actions.get(currentThread());
      if (action instanceof Runnable)
        ping_actions.remove(currentThread());
      if (ping_actions.isEmpty()) ping_anyActions = false;
    }
    
    if (action instanceof Runnable)
      ((Runnable) action).run();
    else if (eq(action, "cancelled"))
      throw fail("Thread cancelled.");
  }
  
  return false;
} catch (Exception __e) { throw rethrow(__e); } }
static boolean nempty(Collection c) {
  return !isEmpty(c);
}

static boolean nempty(CharSequence s) {
  return !isEmpty(s);
}

static boolean nempty(Object[] o) {
  return !isEmpty(o);
}

static boolean nempty(Map m) {
  return !isEmpty(m);
}

static boolean nempty(Iterator i) {
  return i != null && i.hasNext();
}
static boolean isFalse(Object o) {
  return eq(false, o);
}
  static ThreadLocal<String> loadPage_charset = new ThreadLocal();
  static boolean loadPage_allowGzip = true, loadPage_debug;
  static boolean loadPage_anonymous; // don't send computer ID
  static int loadPage_verboseness = 100000;
  static int loadPage_retries = 60; // seconds
  static ThreadLocal<Boolean> loadPage_silent = new ThreadLocal();

  public static String loadPageSilently(String url) { try {
    return loadPageSilently(new URL(loadPage_preprocess(url)));
  } catch (Exception __e) { throw rethrow(__e); } }

  public static String loadPageSilently(URL url) { try {
    IOException e = null;
    for (int tries = 0; tries < loadPage_retries; tries++)
      try {
        URLConnection con = openConnection(url);
        return loadPage(con, url);
      } catch (IOException _e) {
        e = _e;
        if (loadPageThroughProxy_enabled) {
          print("Trying proxy because of: " + e);
          try {
            return loadPageThroughProxy(str(url));
          } catch (Throwable e2) {
            print("  " + exceptionToStringShort(e2));
          }
        } else if (loadPage_debug)
          print(e);
        sleepSeconds(1);
      }
    throw e;
  } catch (Exception __e) { throw rethrow(__e); } }

  static String loadPage_preprocess(String url) {  
    if (url.startsWith("tb/"))
      url = "tinybrain.de:8080/" + url;
    if (url.indexOf("://") < 0)
      url = "http://" + url;
    return url;
  }
  
  public static String loadPage(String url) { try {
    url = loadPage_preprocess(url);
    if (!isTrue(loadPage_silent.get()))
      print("Loading: " + hideCredentials(url));
    return loadPageSilently(new URL(url));
  } catch (Exception __e) { throw rethrow(__e); } }
  
  public static String loadPage(URL url) {
    print("Loading: " + hideCredentials(url.toExternalForm()));
    return loadPageSilently(url);
  }

  public static String loadPage(URLConnection con, URL url) throws IOException {
    try {
      if (!loadPage_anonymous)
        setHeaders(con);
      if (loadPage_allowGzip)
        con.setRequestProperty("Accept-Encoding", "gzip");
    } catch (Throwable e) {} // fails if within doPost
    String contentType = con.getContentType();
    if (contentType == null)
      throw new IOException("Page could not be read: " + url);
    //print("Content-Type: " + contentType);
    String charset = loadPage_charset == null ? null : loadPage_charset.get();
    if (charset == null) charset = loadPage_guessCharset(contentType);
    
    InputStream in = con.getInputStream();
    if ("gzip".equals(con.getContentEncoding())) {
      if (loadPage_debug)
        print("loadPage: Using gzip.");
      in = new GZIPInputStream(in);
    }
    Reader r = new InputStreamReader(in, charset);
    
    StringBuilder buf = new StringBuilder();
    int n = 0;
    while (true) {
      int ch = r.read();
      if (ch < 0)
        break;
      buf.append((char) ch);
      ++n;
      if ((n % loadPage_verboseness) == 0) print("  " + n + " chars read");
    }
    return buf.toString();
  }
  
  static String loadPage_guessCharset(String contentType) {
    Pattern p = Pattern.compile("text/[a-z]+;\\s*charset=([^\\s]+)\\s*");
    Matcher m = p.matcher(contentType);
    String match = m.matches() ? m.group(1) : null;
    if (loadPage_debug)
      print("loadPage: contentType=" + contentType + ", match: " + match);
    /* If Content-Type doesn't match this pre-conception, choose default and hope for the best. */
    return or(match, "ISO-8859-1");
  }

// usually L<S>
static String fromLines(Collection lines) {
  StringBuilder buf = new StringBuilder();
  if (lines != null)
    for (Object line : lines)
      buf.append(str(line)).append('\n');
  return buf.toString();
}

static String fromLines(String... lines) {
  return fromLines(asList(lines));
}
static boolean eq(Object a, Object b) {
  return a == null ? b == null : a == b || a.equals(b);
}
static String standardCredentials() {
  String user = standardCredentialsUser();
  String pass = standardCredentialsPass();
  if (nempty(user) && nempty(pass))
    return "&_user=" + urlencode(user) + "&_pass=" + urlencode(pass);
  return "";
}
public static long parseSnippetID(String snippetID) {
  long id = Long.parseLong(shortenSnippetID(snippetID));
  if (id == 0) throw fail("0 is not a snippet ID");
  return id;
}
static File getGlobalCache() {
  File file = new File(userHome(), ".tinybrain/snippet-cache");
  file.mkdirs();
  return file;
}

/** writes safely (to temp file, then rename) */
static void saveTextFile(String fileName, String contents) throws IOException {
  CriticalAction action = beginCriticalAction("Saving file " + fileName + " (" + l(contents) + " chars)");
  try {
    File file = new File(fileName);
    File parentFile = file.getParentFile();
    if (parentFile != null)
      parentFile.mkdirs();
    String tempFileName = fileName + "_temp";
    File tempFile = new File(tempFileName);
    if (contents != null) {
      if (tempFile.exists()) try {
        String saveName = tempFileName + ".saved." + now();
        copyFile(tempFile, new File(saveName));
      } catch (Throwable e) { printStackTrace(e); }
      FileOutputStream fileOutputStream = newFileOutputStream(tempFile.getPath());
      OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream, "UTF-8");
      PrintWriter printWriter = new PrintWriter(outputStreamWriter);
      printWriter.print(contents);
      printWriter.close();
    }
    
    if (file.exists() && !file.delete())
      throw new IOException("Can't delete " + fileName);
  
    if (contents != null)
      if (!tempFile.renameTo(file))
        throw new IOException("Can't rename " + tempFile + " to " + file);
  } finally {
    action.done();
  }
}

static void saveTextFile(File fileName, String contents) { try {
  saveTextFile(fileName.getPath(), contents);
} catch (Exception __e) { throw rethrow(__e); } }

static List<String> toLines(File f) {
  return toLines(loadTextFile(f));
}

  public static List<String> toLines(String s) {
    List<String> lines = new ArrayList<String>();
    if (s == null) return lines;
    int start = 0;
    while (true) {
      int i = toLines_nextLineBreak(s, start);
      if (i < 0) {
        if (s.length() > start) lines.add(s.substring(start));
        break;
      }

      lines.add(s.substring(start, i));
      if (s.charAt(i) == '\r' && i+1 < s.length() && s.charAt(i+1) == '\n')
        i += 2;
      else
        ++i;

      start = i;
    }
    return lines;
  }

  private static int toLines_nextLineBreak(String s, int start) {
    for (int i = start; i < s.length(); i++) {
      char c = s.charAt(i);
      if (c == '\r' || c == '\n')
        return i;
    }
    return -1;
  }
static String md5(String text) { try {
  if (text == null) return "-";
  return bytesToHex(md5_impl(text.getBytes("UTF-8"))); // maybe different than the way PHP does it...
} catch (Exception __e) { throw rethrow(__e); } }

static String md5(byte[] data) {
  if (data == null) return "-";
  return bytesToHex(md5_impl(data));
}

static MessageDigest md5_md;

/*static byte[] md5_impl(byte[] data) ctex {
  if (md5_md == null)
    md5_md = MessageDigest.getInstance("MD5");
  return ((MessageDigest) md5_md.clone()).digest(data);
}*/

static byte[] md5_impl(byte[] data) { try {
  return MessageDigest.getInstance("MD5").digest(data);
} catch (Exception __e) { throw rethrow(__e); } }

static String md5(File file) { try {
  return md5(loadBinaryFile(file));
} catch (Exception __e) { throw rethrow(__e); } }


static List<CriticalAction> beginCriticalAction_inFlight = synchroList();

static class CriticalAction {
  String description;
  
  CriticalAction() {}
  CriticalAction(String description) {
  this.description = description;}
  
  void done() {
    beginCriticalAction_inFlight.remove(this);
  }
}

static CriticalAction beginCriticalAction(String description) {
  ping();
  CriticalAction c = new CriticalAction(description);
  beginCriticalAction_inFlight.add(c);
  return c;
}

static void cleanMeUp_beginCriticalAction() {
  int n = 0;
  while (nempty(beginCriticalAction_inFlight)) {
    int m = l(beginCriticalAction_inFlight);
    if (m != n) {
      n = m;
      try {
        print("Waiting for " + n(n, "critical actions") + ": " + join(", ", collect(beginCriticalAction_inFlight, "description")));
      } catch (Throwable __e) { printStackTrace2(__e); }
    }
    sleepInCleanUp(10);
  }
}
static String urlencode(String x) {
  try {
    return URLEncoder.encode(unnull(x), "UTF-8");
  } catch (UnsupportedEncodingException e) { throw new RuntimeException(e); }
}
static <A> ArrayList<A> asList(A[] a) {
  return new ArrayList<A>(Arrays.asList(a));
}

static ArrayList<Integer> asList(int[] a) {
  ArrayList<Integer> l = new ArrayList();
  for (int i : a) l.add(i);
  return l;
}

static <A> ArrayList<A> asList(Iterable<A> s) {
  if (s instanceof ArrayList) return (ArrayList) s;
  ArrayList l = new ArrayList();
  if (s != null)
    for (A a : s)
      l.add(a);
  return l;
}

static <A> ArrayList<A> asList(Enumeration<A> e) {
  ArrayList l = new ArrayList();
  if (e != null)
    while (e.hasMoreElements())
      l.add(e.nextElement());
  return l;
}
  public static String bytesToHex(byte[] bytes) {
    return bytesToHex(bytes, 0, bytes.length);
  }

  public static String bytesToHex(byte[] bytes, int ofs, int len) {
    StringBuilder stringBuilder = new StringBuilder(len*2);
    for (int i = 0; i < len; i++) {
      String s = "0" + Integer.toHexString(bytes[ofs+i]);
      stringBuilder.append(s.substring(s.length()-2, s.length()));
    }
    return stringBuilder.toString();
  }

static Object mc() {
  return getMainClass();
}
// TODO: test if android complains about this
static boolean isAWTThread() {
  if (isAndroid()) return false;
  if (isHeadless()) return false;
  return isAWTThread_awt();
}

static boolean isAWTThread_awt() {
  return SwingUtilities.isEventDispatchThread();
}
static String shortenSnippetID(String snippetID) {
  if (snippetID.startsWith("#"))
    snippetID = snippetID.substring(1);
  String httpBlaBla = "http://tinybrain.de/";
  if (snippetID.startsWith(httpBlaBla))
    snippetID = snippetID.substring(httpBlaBla.length());
  return "" + parseLong(snippetID);
}
static Thread currentThread() {
  return Thread.currentThread();
}
static Throwable printStackTrace(Throwable e) {
  // we go to system.out now - system.err is nonsense
  print(getStackTrace(e));
  return e;
}

static void printStackTrace() {
  printStackTrace(new Throwable());
}

static void printStackTrace(String msg) {
  printStackTrace(new Throwable(msg));
}

static void printStackTrace(String indent, Throwable e) {
  if (endsWithLetter(indent)) indent += " ";
  printIndent(indent, getStackTrace(e));
}
static URLConnection openConnection(URL url) { try {
  ping();
  return url.openConnection();
} catch (Exception __e) { throw rethrow(__e); } }
static String standardCredentialsUser() {
  return trim(loadTextFile(new File(userHome(), ".tinybrain/username")));
}
static String str(Object o) {
  return o == null ? "null" : o.toString();
}

static String str(char[] c) {
  return new String(c);
}
static RuntimeException fail() {
  throw new RuntimeException("fail");
}

static RuntimeException fail(Throwable e) {
  throw asRuntimeException(e);
}

static RuntimeException fail(Object msg) {
  throw new RuntimeException(String.valueOf(msg));
}

static RuntimeException fail(String msg) {
  throw new RuntimeException(unnull(msg));
}
 
static RuntimeException fail(String msg, Throwable innerException) {
  throw new RuntimeException(msg, innerException);
}

public static void copyFile(File src, File dest) { try {
  mkdirsForFile(dest);
  FileInputStream inputStream = new FileInputStream(src.getPath());
  FileOutputStream outputStream = newFileOutputStream(dest.getPath());
  try {
    copyStream(inputStream, outputStream);
    inputStream.close();
  } finally {
    outputStream.close();
  }
} catch (Exception __e) { throw rethrow(__e); } }
static void sleepSeconds(double s) {
  if (s > 0) sleep(round(s*1000));
}
static String _userHome;
static String userHome() {
  if (_userHome == null) {
    if (isAndroid())
      _userHome = "/storage/sdcard0/";
    else
      _userHome = System.getProperty("user.home");
    //System.out.println("userHome: " + _userHome);
  }
  return _userHome;
}

static File userHome(String path) {
  return new File(userDir(), path);
}
static long now_virtualTime;
static long now() {
  return now_virtualTime != 0 ? now_virtualTime : System.currentTimeMillis();
}

static String hideCredentials(String url) {
  return url.replaceAll("&_pass=[^&]*", "&_pass=<hidden>");
}
static FileOutputStream newFileOutputStream(File path) throws IOException {
  return newFileOutputStream(path.getPath());
}

static FileOutputStream newFileOutputStream(String path) throws IOException {
  return newFileOutputStream(path, false);
}

static FileOutputStream newFileOutputStream(String path, boolean append) throws IOException {
  FileOutputStream f = new // Line break for ancient translator
    FileOutputStream(path, append);
  callJavaX("registerIO", f, path, true);
  return f;
}
static void setHeaders(URLConnection con) throws IOException {
  String computerID = getComputerID_quick();
  if (computerID != null) try {
    con.setRequestProperty("X-ComputerID", computerID);
    con.setRequestProperty("X-OS", System.getProperty("os.name") + " " + System.getProperty("os.version"));
  } catch (Throwable e) {
    //printShortException(e);
  }
}
static <A> A or(A a, A b) {
  return a != null ? a : b;
}
static boolean isEmpty(Collection c) {
  return c == null || c.isEmpty();
}

static boolean isEmpty(CharSequence s) {
  return s == null || s.length() == 0;
}

static boolean isEmpty(Object[] a) {
  return a == null || a.length == 0;
}

static boolean isEmpty(Map map) {
  return map == null || map.isEmpty();
}
static String exceptionToStringShort(Throwable e) {
  e = getInnerException(e);
  String msg = unnull(e.getMessage());
  if (msg.indexOf("Error") < 0 && msg.indexOf("Exception") < 0)
    return baseClassName(e) + ": " + msg;
  else
    return msg;
}
static int l(Object[] a) { return a == null ? 0 : a.length; }
static int l(boolean[] a) { return a == null ? 0 : a.length; }
static int l(byte[] a) { return a == null ? 0 : a.length; }
static int l(int[] a) { return a == null ? 0 : a.length; }
static int l(float[] a) { return a == null ? 0 : a.length; }
static int l(char[] a) { return a == null ? 0 : a.length; }
static int l(Collection c) { return c == null ? 0 : c.size(); }
static int l(Map m) { return m == null ? 0 : m.size(); }
static int l(CharSequence s) { return s == null ? 0 : s.length(); } static long l(File f) { return f == null ? 0 : f.length(); }

static int l(Object o) {
  return o instanceof String ? l((String) o)
    : o instanceof Map ? l((Map) o)
    : l((Collection) o); // incomplete
}




static boolean isTrue(Object o) {
  if (o instanceof Boolean)
    return ((Boolean) o).booleanValue();
  if (o == null) return false;
  throw fail(getClassName(o));
}
static String standardCredentialsPass() {
  return trim(loadTextFile(new File(userHome(), ".tinybrain/userpass")));
}
public static byte[] loadBinaryFile(String fileName) {
 try {
  if (!new File(fileName).exists())
    return null;

  FileInputStream in = new FileInputStream(fileName);

  byte buf[] = new byte[1024];
  ByteArrayOutputStream out = new ByteArrayOutputStream();
  int l;
  while (true) {
    l = in.read(buf);
    if (l <= 0) break;
    out.write(buf, 0, l);
  }
  in.close();
  return out.toByteArray();
 } catch (IOException e) { throw new RuntimeException(e); }
}

public static byte[] loadBinaryFile(File file) {
  return loadBinaryFile(file.getPath());
}

static Map synchroHashMap() {
  return Collections.synchronizedMap(new HashMap());
}

static final boolean loadPageThroughProxy_enabled = false;

static String loadPageThroughProxy(String url) {
  return null;
}


static Boolean isHeadless_cache;

static boolean isHeadless() {
  if (isHeadless_cache != null) return isHeadless_cache;
  if (GraphicsEnvironment.isHeadless()) return isHeadless_cache = true;
  
  // Also check if AWT actually works.
  // If DISPLAY variable is set but no X server up, this will notice.
  
  try {
    SwingUtilities.isEventDispatchThread();
    return isHeadless_cache = false;
  } catch (Throwable e) { return isHeadless_cache = true; }
}
static String getComputerID_quick() {
  File file = new File(userHome(), ".tinybrain/computer-id");
  return assertNempty(loadTextFile(file.getPath(), null));
}
static void printIndent(Object o) {
  print(indentx(str(o)));
}

static void printIndent(String indent, Object o) {
  print(indentx(indent, str(o)));
}

static void printIndent(int indent, Object o) {
  print(indentx(indent, str(o)));
}
static RuntimeException asRuntimeException(Throwable t) {
  return t instanceof RuntimeException ? (RuntimeException) t : new RuntimeException(t);
}
static String getStackTrace(Throwable throwable) {
  StringWriter writer = new StringWriter();
  throwable.printStackTrace(new PrintWriter(writer));
  return writer.toString();
}
static String trim(String s) { return s == null ? null : s.trim(); }
static String trim(StringBuilder buf) { return buf.toString().trim(); }
static String trim(StringBuffer buf) { return buf.toString().trim(); }
  public static String join(String glue, Iterable<String> strings) {
    if (strings == null) return "";
    StringBuilder buf = new StringBuilder();
    Iterator<String> i = strings.iterator();
    if (i.hasNext()) {
      buf.append(i.next());
      while (i.hasNext())
        buf.append(glue).append(i.next());
    }
    return buf.toString();
  }
  
  public static String join(String glue, String[] strings) {
    return join(glue, Arrays.asList(strings));
  }
  
  public static String join(Iterable<String> strings) {
    return join("", strings);
  }
  
  public static String join(String[] strings) {
    return join("", strings);
  }

static void sleepInCleanUp(long ms) { try {
  if (ms < 0) return;
  Thread.sleep(ms);
} catch (Exception __e) { throw rethrow(__e); } }
static String getClassName(Object o) {
  return o == null ? "null" : o.getClass().getName();
}
static List collect(Collection c, String field) {
  return collectField(c, field);
}
public static File mkdirsForFile(File file) {
  File dir = file.getParentFile();
  if (dir != null) // is null if file is in current dir
    dir.mkdirs();
  return file;
}

static String unnull(String s) {
  return s == null ? "" : s;
}

static <A> List<A> unnull(List<A> l) {
  return l == null ? emptyList() : l;
}

static <A> Iterable<A> unnull(Iterable<A> i) {
  return i == null ? emptyList() : i;
}

static Object[] unnull(Object[] a) {
  return a == null ? new Object[0] : a;
}

static BitSet unnull(BitSet b) {
  return b == null ? new BitSet() : b;
}
static Object callJavaX(String method, Object... args) {
  return callOpt(getJavaX(), method, args);
}
static void sleep(long ms) {
  ping();
  if (ms < 0) return;
  // allow spin locks
  if (isAWTThread() && ms > 100) throw fail("Should not sleep on AWT thread");
  try {
    Thread.sleep(ms);
  } catch (Exception e) { throw new RuntimeException(e); }
}

static void sleep() { try {
  print("Sleeping.");
  sleepQuietly();
} catch (Exception __e) { throw rethrow(__e); } }
static <A> List<A> synchroList() {
  return Collections.synchronizedList(new ArrayList<A>());
}

static <A> List<A> synchroList(List<A> l) {
  return Collections.synchronizedList(l);
}

static String baseClassName(String className) {
  return substring(className, className.lastIndexOf('.')+1);
}

static String baseClassName(Object o) {
  return baseClassName(getClassName(o));
}
static boolean endsWithLetter(String s) {
  return nempty(s) && isLetter(last(s));
}
static Class getMainClass() {
  return main.class;
}

static Class getMainClass(Object o) { try {
  return (o instanceof Class ? (Class) o : o.getClass()).getClassLoader().loadClass("main");
} catch (Exception __e) { throw rethrow(__e); } }
static Throwable getInnerException(Throwable e) {
  while (e.getCause() != null)
    e = e.getCause();
  return e;
}
static String n(long l, String name) {
  return l + " " + (l == 1 ? singular(name) : getPlural(name));
}

static String n(Collection l, String name) {
  return n(l(l), name);
}

static String n(Map m, String name) {
  return n(l(m), name);
}

static String n(Object[] a, String name) {
  return n(l(a), name);
}


static long round(double d) {
  return Math.round(d);
}
static long parseLong(String s) {
  if (s == null) return 0;
  return Long.parseLong(dropSuffix("L", s));
}

static long parseLong(Object s) {
  return Long.parseLong((String) s);
}
static void copyStream(InputStream in, OutputStream out) { try {
  byte[] buf = new byte[65536];
  while (true) {
    int n = in.read(buf);
    if (n <= 0) return;
    out.write(buf, 0, n);
  }
} catch (Exception __e) { throw rethrow(__e); } }
static File userDir() {
  return new File(userHome());
}

static File userDir(String path) {
  return new File(userHome(), path);
}
static int isAndroid_flag;

static boolean isAndroid() {
  if (isAndroid_flag == 0)
    isAndroid_flag = System.getProperty("java.vendor").toLowerCase().indexOf("android") >= 0 ? 1 : -1;
  return isAndroid_flag > 0;
}



static String indentx(String s) {
  return indentx(indent_default, s);
}

static String indentx(int n, String s) {
  return dropSuffix(repeat(' ', n), indent(n, s));
}

static String indentx(String indent, String s) {
  return dropSuffix(indent, indent(indent, s));
}
static <A> A last(List<A> l) {
  return l.isEmpty() ? null : l.get(l.size()-1);
}

static char last(String s) {
  return empty(s) ? '#' : s.charAt(l(s)-1);
}

static int last(int[] a) {
  return l(a) != 0 ? a[l(a)-1] : 0;
}
static List<String> getPlural_specials = ll("sheep", "fish");

static String getPlural(String s) {
  if (containsIgnoreCase(getPlural_specials, s)) return s;
  if (ewic(s, "y")) return dropSuffixIgnoreCase("y", s) + "ies";
  if (ewic(s, "ss")) return s + "es";
  if (ewic(s, "s")) return s;
  return s + "s";
}
static Map<String, String> singular_specials = litmap(
  "children", "child", "images", "image", "chess", "chess");
  
static Set<String> singular_specials2 = litset("time", "machine");

static String singular(String s) {
  if (s == null) return null;
  { String _a_1 = singular_specials.get(s); if (!empty(_a_1)) return _a_1; }
  if (singular_specials2.contains(dropSuffix("s", s)))
    return dropSuffix("s", s);
  if (s.endsWith("ness")) return s;
  if (s.endsWith("ges")) return dropSuffix("s", s);
  s = dropSuffix("es", s);
  s = dropSuffix("s", s);
  return s;
}
static Object callOpt(Object o) {
  if (o == null) return null;
  return callF(o);
}

static Object callOpt(Object o, String method, Object... args) {
  try {
    if (o == null) return null;
    if (o instanceof Class) {
      Method m = callOpt_findStaticMethod((Class) o, method, args, false);
      if (m == null) return null;
      m.setAccessible(true);
      return m.invoke(null, args);
    } else {
      Method m = callOpt_findMethod(o, method, args, false);
      if (m == null) return null;
      m.setAccessible(true);
      return m.invoke(o, args);
    }
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Method callOpt_findStaticMethod(Class c, String method, Object[] args, boolean debug) {
  Class _c = c;
  while (c != null) {
    for (Method m : c.getDeclaredMethods()) {
      if (debug)
        System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
      if (!m.getName().equals(method)) {
        if (debug) System.out.println("Method name mismatch: " + method);
        continue;
      }

      if ((m.getModifiers() & Modifier.STATIC) == 0 || !callOpt_checkArgs(m, args, debug))
        continue;

      return m;
    }
    c = c.getSuperclass();
  }
  return null;
}

static Method callOpt_findMethod(Object o, String method, Object[] args, boolean debug) {
  Class c = o.getClass();
  while (c != null) {
    for (Method m : c.getDeclaredMethods()) {
      if (debug)
        System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
      if (m.getName().equals(method) && callOpt_checkArgs(m, args, debug))
        return m;
    }
    c = c.getSuperclass();
  }
  return null;
}

private static boolean callOpt_checkArgs(Method m, Object[] args, boolean debug) {
  Class<?>[] types = m.getParameterTypes();
  if (types.length != args.length) {
    if (debug)
      System.out.println("Bad parameter length: " + args.length + " vs " + types.length);
    return false;
  }
  for (int i = 0; i < types.length; i++)
    if (!(args[i] == null || isInstanceX(types[i], args[i]))) {
      if (debug)
        System.out.println("Bad parameter " + i + ": " + args[i] + " vs " + types[i]);
      return false;
    }
  return true;
}


static String substring(String s, int x) {
  return substring(s, x, l(s));
}

static String substring(String s, int x, int y) {
  if (s == null) return null;
  if (x < 0) x = 0;
  if (x > s.length()) return "";
  if (y < x) y = x;
  if (y > s.length()) y = s.length();
  return s.substring(x, y);
}


static boolean isLetter(char c) {
  return Character.isLetter(c);
}
static List emptyList() {
  return new ArrayList();
  //ret Collections.emptyList();
}
static void sleepQuietly() { try {
  assertFalse(isAWTThread());
  synchronized(main.class) { main.class.wait(); }
} catch (Exception __e) { throw rethrow(__e); } }
static Class __javax;

static Class getJavaX() {
  return __javax;
}
static List collectField(Collection c, String field) {
  List l = new ArrayList();
  for (Object a : c)
    l.add(getOpt(a, field));
  return l;
}
static String dropSuffix(String suffix, String s) {
  return s.endsWith(suffix) ? s.substring(0, l(s)-l(suffix)) : s;
}
static <A> A assertNempty(A a) {
  if (empty(a))
    throw fail("empty: " + a);
  return a;
}


static WeakHashMap<Class, ArrayList<Method>> callF_cache = new WeakHashMap();

static Object callF(Object f, Object... args) { try {
  if (f instanceof String)
    return callMC((String) f, args);
  if (f instanceof Runnable) {
    ((Runnable) f).run();
    return null;
  }
  if (f == null) return null;
  
  Class c = f.getClass();
  ArrayList<Method> methods;
  synchronized(callF_cache) {
    methods = callF_cache.get(c);
    if (methods == null)
      methods = callF_makeCache(c);
  }
  
  int n = l(methods);
  if (n == 0) throw fail("No get method in " + getClassName(c));
  if (n == 1) return methods.get(0).invoke(f, args);
  for (int i = 0; i < n; i++) {
    Method m = methods.get(i);
    if (call_checkArgs(m, args, false))
      return m.invoke(f, args);
  }
  throw fail("No matching get method in " + getClassName(c));
} catch (Exception __e) { throw rethrow(__e); } }

// used internally
static ArrayList<Method> callF_makeCache(Class c) {
  ArrayList<Method> l = new ArrayList();
  Class _c = c;
  do {
    for (Method m : _c.getDeclaredMethods())
      if (m.getName().equals("get")) {
        m.setAccessible(true);
        l.add(m);
      }
    if (!l.isEmpty()) break;
    _c = _c.getSuperclass();
  } while (_c != null);
  callF_cache.put(c, l);
  return l;
}
static <A> HashSet<A> litset(A... items) {
  return lithashset(items);
}
static Map litmap(Object... x) {
  TreeMap map = new TreeMap();
  litmap_impl(map, x);
  return map;
}

static void litmap_impl(Map map, Object... x) {
  for (int i = 0; i < x.length-1; i += 2)
    if (x[i+1] != null)
      map.put(x[i], x[i+1]);
}
static String dropSuffixIgnoreCase(String suffix, String s) {
  return ewic(s, suffix) ? s.substring(0, l(s)-l(suffix)) : s;
}
static boolean ewic(String a, String b) {
  return endsWithIgnoreCase(a, b);
}
static <A> List<A> ll(A... a) {
  return litlist(a);
}
static boolean empty(Collection c) {
  return isEmpty(c);
}

static boolean empty(String s) {
  return isEmpty(s);
}

static boolean empty(Map map) {
  return map == null || map.isEmpty();
}

static boolean empty(Object[] o) {
  return o == null || o.length == 0;
}

static boolean empty(Object o) {
  if (o instanceof Collection) return empty((Collection) o);
  if (o instanceof String) return empty((String) o);
  if (o instanceof Map) return empty((Map) o);
  if (o instanceof Object[]) return empty((Object[]) o);
  throw fail("unknown type for 'empty': " + getType(o));
}

static boolean empty(float[] a) { return a == null || a.length == 0; }
// extended over Class.isInstance() to handle primitive types
static boolean isInstanceX(Class type, Object arg) {
  if (type == boolean.class) return arg instanceof Boolean;
  if (type == int.class) return arg instanceof Integer;
  if (type == long.class) return arg instanceof Long;
  if (type == float.class) return arg instanceof Float;
  if (type == short.class) return arg instanceof Short;
  if (type == char.class) return arg instanceof Character;
  if (type == byte.class) return arg instanceof Byte;
  if (type == double.class) return arg instanceof Double;
  return type.isInstance(arg);
}
static int indent_default = 2;

static String indent(int indent) {
  return repeat(' ', indent);
}

static String indent(int indent, String s) {
  return indent(repeat(' ', indent), s);
}

static String indent(String indent, String s) {
  return indent + s.replace("\n", "\n" + indent);
}

static String indent(String s) {
  return indent(indent_default, s);
}

static List<String> indent(String indent, List<String> lines) {
  List<String> l = new ArrayList();
  for (String s : lines)
    l.add(indent + s);
  return l;
}
static void assertFalse(Object o) {
  assertEquals(false, o);
}
  
static boolean assertFalse(boolean b) {
  if (b) throw fail("oops");
  return b;
}

static boolean assertFalse(String msg, boolean b) {
  if (b) throw fail(msg);
  return b;
}

static String repeat(char c, int n) {
  n = Math.max(n, 0);
  char[] chars = new char[n];
  for (int i = 0; i < n; i++)
    chars[i] = c;
  return new String(chars);
}

static <A> List<A> repeat(A a, int n) {
  List<A> l = new ArrayList();
  for (int i = 0; i < n; i++)
    l.add(a);
  return l;
}

static <A> List<A> repeat(int n, A a) {
  return repeat(a, n);
}
static boolean containsIgnoreCase(List<String> l, String s) {
  for (String x : l)
    if (eqic(x, s))
      return true;
  return false;
}

static boolean containsIgnoreCase(String[] l, String s) {
  for (String x : l)
    if (eqic(x, s))
      return true;
  return false;
}

static boolean containsIgnoreCase(String s, char c) {
  return indexOfIgnoreCase(s, String.valueOf(c)) >= 0;
}

static boolean containsIgnoreCase(String a, String b) {
  return indexOfIgnoreCase(a, b) >= 0;
}
static Object getOpt(Object o, String field) {
  return getOpt_cached(o, field);
}

static Object getOpt_raw(Object o, String field) {
  try {
    Field f = getOpt_findField(o.getClass(), field);
    if (f == null) return null;
    f.setAccessible(true);
    return f.get(o);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Object getOpt(Class c, String field) {
  try {
    if (c == null) return null;
    Field f = getOpt_findStaticField(c, field);
    if (f == null) return null;
    f.setAccessible(true);
    return f.get(null);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Field getOpt_findStaticField(Class<?> c, String field) {
  Class _c = c;
  do {
    for (Field f : _c.getDeclaredFields())
      if (f.getName().equals(field) && (f.getModifiers() & Modifier.STATIC) != 0)
        return f;
    _c = _c.getSuperclass();
  } while (_c != null);
  return null;
}



static final HashMap<String, List<Method>> callMC_cache = new HashMap();
static String callMC_key;
static Method callMC_value;

// varargs assignment fixer for a single string array argument
static Object callMC(String method, String[] arg) {
  return callMC(method, new Object[] {arg});
}

static Object callMC(String method, Object... args) { try {
  Method me;
  synchronized(callMC_cache) {
    me = method == callMC_key ? callMC_value : null;
  }
  if (me != null) return callMC_value.invoke(null, args);

  List<Method> m;
  synchronized(callMC_cache) {
    m = callMC_cache.get(method);
  }
  if (m == null) {
    if (callMC_cache.isEmpty()) {
      callMC_makeCache();
      m = callMC_cache.get(method);
    }
    if (m == null) throw fail("Method named " + method + " not found in main");
  }
  int n = m.size();
  if (n == 1) {
    me = m.get(0);
    synchronized(callMC_cache) {
      callMC_key = method;
      callMC_value = me;
    }
    return me.invoke(null, args);
  }
  for (int i = 0; i < n; i++) {
    me = m.get(i);
    if (call_checkArgs(me, args, false))
      return me.invoke(null, args);
  }
  throw fail("No method called " + method + " with matching arguments found in main");
} catch (Exception __e) { throw rethrow(__e); } }

static void callMC_makeCache() {
  synchronized(callMC_cache) {
    callMC_cache.clear();
    Class _c = (Class) mc(), c = _c;
    while (c != null) {
      for (Method m : c.getDeclaredMethods())
        if ((m.getModifiers() & Modifier.STATIC) != 0) {
          m.setAccessible(true);
          multiMapPut(callMC_cache, m.getName(), m);
        }
      c = c.getSuperclass();
    }
  }
}
static String getType(Object o) {
  return getClassName(o);
}
static boolean endsWithIgnoreCase(String a, String b) {
  return a != null && l(a) >= l(b) && a.regionMatches(true, l(a)-l(b), b, 0, l(b));
}
static <A> ArrayList<A> litlist(A... a) {
  return new ArrayList<A>(Arrays.asList(a));
}
static <A> A assertEquals(Object x, A y) {
  return assertEquals(null, x, y);
}

static <A> A assertEquals(String msg, Object x, A y) {
  if (!(x == null ? y == null : x.equals(y)))
    throw fail((msg != null ? msg + ": " : "") + y + " != " + x);
  return y;
}
static Field getOpt_findField(Class<?> c, String field) {
  Class _c = c;
  do {
    for (Field f : _c.getDeclaredFields())
      if (f.getName().equals(field))
        return f;
    _c = _c.getSuperclass();
  } while (_c != null);
  return null;
}
// works on lists and strings and null

static int indexOfIgnoreCase(Object a, Object b) {
  if (a == null) return -1;
  if (a instanceof String) {
     Matcher m = Pattern.compile((String) b, Pattern.CASE_INSENSITIVE + Pattern.LITERAL).matcher((String) a);
     if (m.find()) return m.start(); else return -1;
  }
  if (a instanceof List) {
    for (int i = 0; i < ((List) a).size(); i++) {
      Object o = ((List) a).get(i);
      if (o != null && ((String) o).equalsIgnoreCase((String) b))
        return i;
    }
    return -1;
  }
  throw fail("Unknown type: " + a);
}
static <A> HashSet<A> lithashset(A... items) {
  HashSet<A> set = new HashSet();
  for (A a : items) set.add(a);
  return set;
}
  static Object call(Object o) {
    return callFunction(o);
  }
  
  // varargs assignment fixer for a single string array argument
  static Object call(Object o, String method, String[] arg) {
    return call(o, method, new Object[] {arg});
  }
  
  static Object call(Object o, String method, Object... args) {
    try {
      if (o instanceof Class) {
        Method m = call_findStaticMethod((Class) o, method, args, false);
        m.setAccessible(true);
        return m.invoke(null, args);
      } else {
        Method m = call_findMethod(o, method, args, false);
        m.setAccessible(true);
        return m.invoke(o, args);
      }
    } catch (Exception e) {
      throw e instanceof RuntimeException ? (RuntimeException) e : new RuntimeException(e);
    }
  }

  static Method call_findStaticMethod(Class c, String method, Object[] args, boolean debug) {
    Class _c = c;
    while (c != null) {
      for (Method m : c.getDeclaredMethods()) {
        if (debug)
          System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
        if (!m.getName().equals(method)) {
          if (debug) System.out.println("Method name mismatch: " + method);
          continue;
        }

        if ((m.getModifiers() & Modifier.STATIC) == 0 || !call_checkArgs(m, args, debug))
          continue;

        return m;
      }
      c = c.getSuperclass();
    }
    throw new RuntimeException("Method '" + method + "' (static) with " + args.length + " parameter(s) not found in " + _c.getName());
  }

  static Method call_findMethod(Object o, String method, Object[] args, boolean debug) {
    Class c = o.getClass();
    while (c != null) {
      for (Method m : c.getDeclaredMethods()) {
        if (debug)
          System.out.println("Checking method " + m.getName() + " with " + m.getParameterTypes().length + " parameters");;
        if (m.getName().equals(method) && call_checkArgs(m, args, debug))
          return m;
      }
      c = c.getSuperclass();
    }
    throw new RuntimeException("Method '" + method + "' (non-static) with " + args.length + " parameter(s) not found in " + o.getClass().getName());
  }

  private static boolean call_checkArgs(Method m, Object[] args, boolean debug) {
    Class<?>[] types = m.getParameterTypes();
    if (types.length != args.length) {
      if (debug)
        System.out.println("Bad parameter length: " + args.length + " vs " + types.length);
      return false;
    }
    for (int i = 0; i < types.length; i++)
      if (!(args[i] == null || isInstanceX(types[i], args[i]))) {
        if (debug)
          System.out.println("Bad parameter " + i + ": " + args[i] + " vs " + types[i]);
        return false;
      }
    return true;
  }


static final WeakHashMap<Class, HashMap<String, Field>> getOpt_cache = new WeakHashMap();
static final HashMap getOpt_special = new HashMap(); // just a marker

static {
  getOpt_cache.put(Class.class, getOpt_special);
  getOpt_cache.put(String.class, getOpt_special);
}

static Object getOpt_cached(Object o, String field) { try {
  if (o == null) return null;

  Class c = o.getClass();
  HashMap<String, Field> map;
  synchronized(getOpt_cache) {
    map = getOpt_cache.get(c);
    if (map == null)
      map = getOpt_makeCache(c);
  }
  
  if (map == getOpt_special) {
    if (o instanceof Class)
      return getOpt((Class) o, field);
    /*if (o instanceof S)
      ret getOpt(getBot((S) o), field);*/
    if (o instanceof Map)
      return ((Map) o).get(field);
  }
    
  Field f = map.get(field);
  if (f != null) return f.get(o);
  
  return null;
} catch (Exception __e) { throw rethrow(__e); } }

// used internally - we are in synchronized block
static HashMap<String, Field> getOpt_makeCache(Class c) {
  HashMap<String, Field> map;
  if (isSubtypeOf(c, Map.class))
    map = getOpt_special;
  else {
    map = new HashMap();
    Class _c = c;
    do {
      for (Field f : _c.getDeclaredFields()) {
        f.setAccessible(true);
        String name = f.getName();
        if (!map.containsKey(name))
          map.put(name, f);
      }
      _c = _c.getSuperclass();
    } while (_c != null);
  }
  getOpt_cache.put(c, map);
  return map;
}
static boolean eqic(String a, String b) {
  if ((a == null) != (b == null)) return false;
  if (a == null) return true;
  return a.equalsIgnoreCase(b);
}


static Object callFunction(Object f, Object... args) {
  return callF(f, args);
}
static boolean isSubtypeOf(Class a, Class b) {
  return b.isAssignableFrom(a); // << always hated that method, let's replace it!
}
static <A, B> void multiMapPut(Map<A, List<B>> map, A a, B b) {
  List<B> l = map.get(a);
  if (l == null)
    map.put(a, l = new ArrayList());
  l.add(b);
}


static abstract class F1<A, B> {
  abstract B get(A a);
}


static class BlockDiff {
  public CopyBlock asCopyBlock() { return null; }
  public NewBlock  asNewBlock () { return null; }
}

static class CopyBlock extends BlockDiff {
  int firstLine, lines;

  CopyBlock(int firstLine, int lines) {
    this.firstLine = firstLine;
    this.lines = lines;
  }

  public CopyBlock asCopyBlock() { return this; }
  public int getFirstLine() { return firstLine; }
  public int getLines() { return lines; }
}

static class NewBlock extends BlockDiff {
  int originalStart;
  List<String> contents;

  NewBlock(int originalStart, List<String> contents) {
    this.originalStart = originalStart;
    this.contents = contents;
  }

  public NewBlock  asNewBlock () { return this; }

  public int getOriginalStart() {
    return originalStart;
  }

  public List<String> getContents() {
    return contents;
  }
}

static class ExplodedLine {
  int type;
  String left, right;
  int leftIndex, rightIndex;

  ExplodedLine(int type, String left, String right, int leftIndex, int rightIndex) {
    this.type = type;
    this.left = left;
    this.right = right;
    this.leftIndex = leftIndex;
    this.rightIndex = rightIndex;
  }
  
  public int getType() {
    return type;
  }

  public String getLeft() {
    return left;
  }

  public String getRight() {
    return right;
  }

  public int getLeftIndex() {
    return leftIndex;
  }

  public int getRightIndex() {
    return rightIndex;
  }
}

static class BlockDiffer {
  public static final int IDENTICAL = 0;
  public static final int DIFFERENT = 1;
  public static final int LEFT_ONLY = 2;
  public static final int RIGHT_ONLY = 3;

  private static void printChange(EGDiff.change change) {
    if (change != null) {
      System.out.println("line0="+change.line0+", line1="+change.line1
        +", inserted="+change.inserted+", deleted="+change.deleted);
      printChange(change.link);
    }
  }


  /** Generates the text content of a Unified-format context diff between 2 files
   *  (NB the 'files-changed' header must be added separately).
   */
  public static List<String> generateUniDiff(List<String> fileA, List<String> fileB, int contextSize) {
    EGDiff diff = new EGDiff(fileA.toArray(), fileB.toArray());
    EGDiff.change change = diff.diff_2(false);

    if (change != null) {
      int inserted, deleted;
      List<String> hunkLines = new ArrayList<String>();
      int cumulExtraLinesBwrtA = 0;

      // Each hunk is generated with a header
      do {
        int line0 = change.line0, line1 = change.line1;
        int changeStart = ((line1 < line0) ? line1 : line0);
        int contextStart = ((changeStart > contextSize) ? changeStart - contextSize : 0);
        int headerPosn = hunkLines.size();

        // Provide the first lines of context
        for (int i = contextStart; i < changeStart; i++)
          //System.out.println(" " + fileA.get(i));
          hunkLines.add(" " + fileA.get(i));

        boolean hunkFinish = false;
        // Step through each change giving the change lines and following context
        do {
          inserted = change.inserted;
          deleted = change.deleted;
          line0 = change.line0;
          line1 = change.line1;

          if (line1 < line0) // An insert comes earlier
            while (inserted-- > 0)
              hunkLines.add("+" + fileB.get(line1++));
          while (deleted-- > 0)
            hunkLines.add("-" + fileA.get(line0++));
          while (inserted-- > 0)
            hunkLines.add("+" + fileB.get(line1++));

          // Lines following are trailing context, identical in fileA and fileB
          // The next change may overlap the context, so check and if so, form one hunk
          EGDiff.change nextChange = change.link;
          int nextChangeStart = fileA.size();
          if (nextChange != null)
            nextChangeStart = ((nextChange.line1 < nextChange.line0) ? nextChange.line1 : nextChange.line0);

          if (nextChangeStart - line0 > contextSize * 2) { // A separate hunk
            nextChangeStart = line0 + contextSize;
            hunkFinish = true;
          }
          if (nextChangeStart > fileA.size())
            nextChangeStart = fileA.size(); // Limit to file size
          while (line0 < nextChangeStart) {
            hunkLines.add(" " + fileA.get(line0++));
            line1++; // Keep in sync with trailing context
          }

          change = change.link;
        } while (!hunkFinish && change != null);

        int hunkStartB = contextStart + cumulExtraLinesBwrtA;
        int hunkTotA = line0 - contextStart;
        int hunkTotB = line1 - hunkStartB;

        hunkLines.add(headerPosn, "@@ -" + (contextStart + 1) + ',' + hunkTotA +
                        " +" + (hunkStartB + 1) + ',' + hunkTotB + " @@");
        cumulExtraLinesBwrtA += hunkTotB - hunkTotA;

      } while (change != null);

      return hunkLines;
    }
    return null;
  }

/* For testing:
  private static void printUniDiff(List<String> fileA, List<String> fileB, int contextSize) {
    List<String> uniDiff = generateUniDiff(fileA, fileB, contextSize);

    if (uniDiff != null)
      for (int j = 0; j < uniDiff.size(); j++)
        System.out.println(uniDiff.get(j));
  }
 */


  public static List<BlockDiff> diffLines(List<String> lines, List<String> reference) {
    List<BlockDiff> diffs = new ArrayList<BlockDiff>();

    EGDiff diff = new EGDiff(reference.toArray(), lines.toArray());
    EGDiff.change change = diff.diff_2(false);
    //printChange(change);
    //printUniDiff(reference, lines, 3);

    int l0 = 0, l1 = 0;
    while (change != null) {
      if (change.line0 > l0 && change.line1 > l1)
        diffs.add(new CopyBlock(l0, change.line0-l0));

      if (change.inserted != 0)
        diffs.add(new NewBlock(change.line1, lines.subList(change.line1, change.line1+change.inserted)));

      l0 = change.line0 + change.deleted;
      l1 = change.line1 + change.inserted;
      change = change.link;
    }

    if (l0 < reference.size())
      diffs.add(new CopyBlock(l0, reference.size()-l0));

    return diffs;
  }

  /** fills files with empty lines to align matching blocks
   *
   * @param file1 first file
   * @param file2 second file
   * @return an array with two lists
   */
  public static List<ExplodedLine> explode(List<String> file1, List<String> file2) {
    List<ExplodedLine> lines = new ArrayList<ExplodedLine>();
    List<BlockDiff> diffs = BlockDiffer.diffLines(file2, file1);
    int lastLineCopied = 0, rightOnlyStart = -1, rightPosition = 0;
    for (int i = 0; i < diffs.size(); i++) {
      BlockDiff diff = diffs.get(i);
      if (diff instanceof CopyBlock) {
        CopyBlock copyBlock = (CopyBlock) diff;
        if (lastLineCopied < copyBlock.getFirstLine()) {
          if (rightOnlyStart >= 0) {
            int overlap = Math.min(lines.size()-rightOnlyStart, copyBlock.getFirstLine()-lastLineCopied);
            //lines.subList(rightOnlyStart, rightOnlyStart+overlap).clear();
            convertRightOnlyToDifferent(lines, rightOnlyStart, overlap, file1, lastLineCopied);
            lastLineCopied += overlap;
          }
          addBlock(lines, LEFT_ONLY, file1, lastLineCopied, copyBlock.getFirstLine(), lastLineCopied, -1);
        }
        addBlock(lines, IDENTICAL, file1, copyBlock.getFirstLine(), copyBlock.getFirstLine()+copyBlock.getLines(),
          copyBlock.getFirstLine(), rightPosition);
        rightPosition += copyBlock.getLines();
        lastLineCopied = copyBlock.getFirstLine()+copyBlock.getLines();
        rightOnlyStart = -1;
      } else if (diff instanceof NewBlock) {
        NewBlock newBlock = (NewBlock) diff;
        /*if (nextDiff instanceof BlockDiffer.CopyBlock) {
          BlockDiffer.CopyBlock copyBlock = (BlockDiffer.CopyBlock) nextDiff;
          copyBlock.getFirstLine()-lastLineCopied*/
        rightOnlyStart = lines.size();
        addBlock(lines, RIGHT_ONLY, newBlock.getContents(), 0, newBlock.getContents().size(), -1, rightPosition);
        rightPosition += newBlock.getContents().size();
      }
    }

    if (rightOnlyStart >= 0) {
      int overlap = Math.min(lines.size()-rightOnlyStart, file1.size()-lastLineCopied);
      //lines.subList(rightOnlyStart, rightOnlyStart+overlap).clear();
      convertRightOnlyToDifferent(lines, rightOnlyStart, overlap, file1, lastLineCopied);
      lastLineCopied += overlap;
    }
    addBlock(lines, LEFT_ONLY, file1, lastLineCopied, file1.size(), lastLineCopied, -1);

    return lines;
  }

  private static void convertRightOnlyToDifferent(List<ExplodedLine> lines, int start, int numLines,
                                                  List<String> leftLines, int leftStart) {
    for (int i = 0; i < numLines; i++) {
      ExplodedLine line = lines.get(start+i);
      lines.set(start+i,
        new ExplodedLine(DIFFERENT, leftLines.get(i+leftStart), line.getRight(), i+leftStart, line.getRightIndex()));
    }
  }

  private static void addBlock(List<ExplodedLine> lines, int type, List<String> srcLines, int start, int end,
                               int leftStart, int rightStart) {
    for (int i = start; i < end; i++)
      lines.add(new ExplodedLine(type, type == RIGHT_ONLY ? "" : srcLines.get(i),
                                       type == LEFT_ONLY ? "" : srcLines.get(i),
                                       type == RIGHT_ONLY ? -1 : i - start + leftStart,
                                       type == LEFT_ONLY ? -1 : i - start + rightStart));
  }

  public static List<ExplodedLine> condense(List<ExplodedLine> lines) {
    List<ExplodedLine> result = new ArrayList<ExplodedLine>();
    for (Iterator<ExplodedLine> i = lines.iterator(); i.hasNext();) {
      ExplodedLine line = i.next();
      if (line.getType() == IDENTICAL) {
        if (result.isEmpty() || result.get(result.size()-1).getType() != IDENTICAL)
          result.add(new ExplodedLine(IDENTICAL, "[...]", "[...]", -1, -1));
      } else
        result.add(line);
    }
    return result;
  }
}

// get purpose 1: access a list/array (safer version of x.get(y))

static <A> A get(List<A> l, int idx) {
  return l != null && idx >= 0 && idx < l(l) ? l.get(idx) : null;
}

static <A> A get(A[] l, int idx) {
  return idx >= 0 && idx < l(l) ? l[idx] : null;
}

// default to false
static boolean get(boolean[] l, int idx) {
  return idx >= 0 && idx < l(l) ? l[idx] : false;
}

// get purpose 2: access a field by reflection or a map

static Object get(Object o, String field) {
  try {
    if (o instanceof Class) return get((Class) o, field);
    
    if (o instanceof Map)
      return ((Map) o).get(field);
      
    Field f = getOpt_findField(o.getClass(), field);
    if (f != null) {
      f.setAccessible(true);
      return f.get(o);
    }
      
    
  } catch (Exception e) {
    throw asRuntimeException(e);
  }
  throw new RuntimeException("Field '" + field + "' not found in " + o.getClass().getName());
}

static Object get_raw(Object o, String field) {
  try {
    Field f = get_findField(o.getClass(), field);
    f.setAccessible(true);
    return f.get(o);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Object get(Class c, String field) {
  try {
    Field f = get_findStaticField(c, field);
    f.setAccessible(true);
    return f.get(null);
  } catch (Exception e) {
    throw new RuntimeException(e);
  }
}

static Field get_findStaticField(Class<?> c, String field) {
  Class _c = c;
  do {
    for (Field f : _c.getDeclaredFields())
      if (f.getName().equals(field) && (f.getModifiers() & Modifier.STATIC) != 0)
        return f;
    _c = _c.getSuperclass();
  } while (_c != null);
  throw new RuntimeException("Static field '" + field + "' not found in " + c.getName());
}

static Field get_findField(Class<?> c, String field) {
  Class _c = c;
  do {
    for (Field f : _c.getDeclaredFields())
      if (f.getName().equals(field))
        return f;
    _c = _c.getSuperclass();
  } while (_c != null);
  throw new RuntimeException("Field '" + field + "' not found in " + c.getName());
}

static RuntimeException rethrow(Throwable e) {
  throw asRuntimeException(e);
}
static Throwable printStackTrace2(Throwable e) {
  // we go to system.out now - system.err is nonsense
  print(getStackTrace2(e));
  return e;
}

static void printStackTrace2() {
  printStackTrace2(new Throwable());
}

static void printStackTrace2(String msg) {
  printStackTrace2(new Throwable(msg));
}

static void printStackTrace2(String indent, Throwable e) {
  if (endsWithLetter(indent)) indent += " ";
  printIndent(indent, getStackTrace2(e));
}


static String getStackTrace2(Throwable throwable) {
  return getStackTrace(throwable) + replacePrefix("java.lang.RuntimeException: ", "FAIL: ",
    str(getInnerException(throwable))) + "\n";
}


static String replacePrefix(String prefix, String replacement, String s) {
  if (!startsWith(s, prefix)) return s;
  return replacement + substring(s, l(prefix));
}


static boolean startsWith(String a, String b) {
  return a != null && a.startsWith(b);
}



static boolean startsWith(List a, List b) {
  if (a == null || l(b) > l(a)) return false;
  for (int i = 0; i < l(b); i++)
    if (neq(a.get(i), b.get(i)))
      return false;
  return true;
}




static boolean neq(Object a, Object b) {
  return !eq(a, b);
}


/**
 * A class to compare vectors of objects.  The result of comparison
 * is a list of <code>change</code> objects which form an
 * edit script.  The objects compared are traditionally lines
 * of text from two files.  Comparison options such as "ignore
 * whitespace" are implemented by modifying the <code>equals</code>
 * and <code>hashcode</code> methods for the objects compared.
 * <p/>
 * The basic algorithm is described in: </br>
 * "An O(ND) Difference Algorithm and its Variations", Eugene Myers,
 * Algorithmica Vol. 1 No. 2, 1986, p 251.
 * <p/>
 * This class outputs different results from GNU diff 1.15 on some
 * inputs.  Our results are actually better (smaller change list, smaller
 * total size of changes), but it would be nice to know why.  Perhaps
 * there is a memory overwrite bug in GNU diff 1.15.
 *
 * @author Stuart D. Gathman, translated from GNU diff 1.15
 *         Copyright (C) 2000  Business Management Systems, Inc.
 *         <p/>
 *         This program is free software; you can redistribute it and/or modify
 *         it under the terms of the GNU General Public License as published by
 *         the Free Software Foundation; either version 1, or (at your option)
 *         any later version.
 *         <p/>
 *         This program is distributed in the hope that it will be useful,
 *         but WITHOUT ANY WARRANTY; without even the implied warranty of
 *         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *         GNU General Public License for more details.
 *         <p/>
 *         You should have received a copy of the <a href=COPYING.txt>
 *         GNU General Public License</a>
 *         along with this program; if not, write to the Free Software
 *         Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

static class EGDiff {

  /**
   * Prepare to find differences between two arrays.  Each element of
   * the arrays is translated to an "equivalence number" based on
   * the result of <code>equals</code>.  The original Object arrays
   * are no longer needed for computing the differences.  They will
   * be needed again later to print the results of the comparison as
   * an edit script, if desired.
   */
  public EGDiff(Object[] a, Object[] b) {
    Hashtable h = new Hashtable(a.length + b.length);
    filevec[0] = new file_data(a, h);
    filevec[1] = new file_data(b, h);
  }

  /**
   * 1 more than the maximum equivalence value used for this or its
   * sibling file.
   */
  private int equiv_max = 1;

  /**
   * When set to true, the comparison uses a heuristic to speed it up.
   * With this heuristic, for files with a constant small density
   * of changes, the algorithm is linear in the file size.
   */
  public boolean heuristic = false;

  /**
   * When set to true, the algorithm returns a guarranteed minimal
   * set of changes.  This makes things slower, sometimes much slower.
   */
  public boolean no_discards = false;

  private int[] xvec, yvec;	/* Vectors being compared. */
  private int[] fdiag;		/* Vector, indexed by diagonal, containing
				   the X coordinate of the point furthest
				   along the given diagonal in the forward
				   search of the edit matrix. */
  private int[] bdiag;		/* Vector, indexed by diagonal, containing
				   the X coordinate of the point furthest
				   along the given diagonal in the backward
				   search of the edit matrix. */
  private int fdiagoff, bdiagoff;
  private final file_data[] filevec = new file_data[2];
  private int cost;

  /**
   * Find the midpoint of the shortest edit script for a specified
   * portion of the two files.
   * <p/>
   * We scan from the beginnings of the files, and simultaneously from the ends,
   * doing a breadth-first search through the space of edit-sequence.
   * When the two searches meet, we have found the midpoint of the shortest
   * edit sequence.
   * <p/>
   * The value returned is the number of the diagonal on which the midpoint lies.
   * The diagonal number equals the number of inserted lines minus the number
   * of deleted lines (counting only lines before the midpoint).
   * The edit cost is stored into COST; this is the total number of
   * lines inserted or deleted (counting only lines before the midpoint).
   * <p/>
   * This function assumes that the first lines of the specified portions
   * of the two files do not match, and likewise that the last lines do not
   * match.  The caller must trim matching lines from the beginning and end
   * of the portions it is going to specify.
   * <p/>
   * Note that if we return the "wrong" diagonal value, or if
   * the value of bdiag at that diagonal is "wrong",
   * the worst this can do is cause suboptimal diff output.
   * It cannot cause incorrect diff output.
   */

  private int diag(int xoff, int xlim, int yoff, int ylim) {
    final int[] fd = fdiag;	// Give the compiler a chance.
    final int[] bd = bdiag;	// Additional help for the compiler.
    final int[] xv = xvec;		// Still more help for the compiler.
    final int[] yv = yvec;		// And more and more . . .
    final int dmin = xoff - ylim;	// Minimum valid diagonal.
    final int dmax = xlim - yoff;	// Maximum valid diagonal.
    final int fmid = xoff - yoff;	// Center diagonal of top-down search.
    final int bmid = xlim - ylim;	// Center diagonal of bottom-up search.
    int fmin = fmid, fmax = fmid;	// Limits of top-down search.
    int bmin = bmid, bmax = bmid;	// Limits of bottom-up search.
    /* True if southeast corner is on an odd
				     diagonal with respect to the northwest. */
    final boolean odd = (fmid - bmid & 1) != 0;

    fd[fdiagoff + fmid] = xoff;
    bd[bdiagoff + bmid] = xlim;

    for (int c = 1; ; ++c) {
      int d;			/* Active diagonal. */
      boolean big_snake = false;

      /* Extend the top-down search by an edit step in each diagonal. */
      if (fmin > dmin)
        fd[fdiagoff + --fmin - 1] = -1;
      else
        ++fmin;
      if (fmax < dmax)
        fd[fdiagoff + ++fmax + 1] = -1;
      else
        --fmax;
      for (d = fmax; d >= fmin; d -= 2) {
        int x, y, oldx, tlo = fd[fdiagoff + d - 1], thi = fd[fdiagoff + d + 1];

        if (tlo >= thi)
          x = tlo + 1;
        else
          x = thi;
        oldx = x;
        y = x - d;
        while (x < xlim && y < ylim && xv[x] == yv[y]) {
          ++x;
          ++y;
        }
        if (x - oldx > 20)
          big_snake = true;
        fd[fdiagoff + d] = x;
        if (odd && bmin <= d && d <= bmax && bd[bdiagoff + d] <= fd[fdiagoff + d]) {
          cost = 2 * c - 1;
          return d;
        }
      }

      /* Similar extend the bottom-up search. */
      if (bmin > dmin)
        bd[bdiagoff + --bmin - 1] = Integer.MAX_VALUE;
      else
        ++bmin;
      if (bmax < dmax)
        bd[bdiagoff + ++bmax + 1] = Integer.MAX_VALUE;
      else
        --bmax;
      for (d = bmax; d >= bmin; d -= 2) {
        int x, y, oldx, tlo = bd[bdiagoff + d - 1], thi = bd[bdiagoff + d + 1];

        if (tlo < thi)
          x = tlo;
        else
          x = thi - 1;
        oldx = x;
        y = x - d;
        while (x > xoff && y > yoff && xv[x - 1] == yv[y - 1]) {
          --x;
          --y;
        }
        if (oldx - x > 20)
          big_snake = true;
        bd[bdiagoff + d] = x;
        if (!odd && fmin <= d && d <= fmax && bd[bdiagoff + d] <= fd[fdiagoff + d]) {
          cost = 2 * c;
          return d;
        }
      }

      /* Heuristic: check occasionally for a diagonal that has made
         lots of progress compared with the edit distance.
         If we have any such, find the one that has made the most
         progress and return it as if it had succeeded.

         With this heuristic, for files with a constant small density
         of changes, the algorithm is linear in the file size.  */

      if (c > 200 && big_snake && heuristic) {
        int best = 0;
        int bestpos = -1;

        for (d = fmax; d >= fmin; d -= 2) {
          int dd = d - fmid;
          if ((fd[fdiagoff + d] - xoff) * 2 - dd > 12 * (c + (dd > 0 ? dd : -dd))) {
            if (fd[fdiagoff + d] * 2 - dd > best
              && fd[fdiagoff + d] - xoff > 20
              && fd[fdiagoff + d] - d - yoff > 20) {
              int k;
              int x = fd[fdiagoff + d];

              /* We have a good enough best diagonal;
                 now insist that it end with a significant snake.  */
              for (k = 1; k <= 20; k++)
                if (xvec[x - k] != yvec[x - d - k])
                  break;

              if (k == 21) {
                best = fd[fdiagoff + d] * 2 - dd;
                bestpos = d;
              }
            }
          }
        }
        if (best > 0) {
          cost = 2 * c - 1;
          return bestpos;
        }

        best = 0;
        for (d = bmax; d >= bmin; d -= 2) {
          int dd = d - bmid;
          if ((xlim - bd[bdiagoff + d]) * 2 + dd > 12 * (c + (dd > 0 ? dd : -dd))) {
            if ((xlim - bd[bdiagoff + d]) * 2 + dd > best
              && xlim - bd[bdiagoff + d] > 20
              && ylim - (bd[bdiagoff + d] - d) > 20) {
              /* We have a good enough best diagonal;
                 now insist that it end with a significant snake.  */
              int k;
              int x = bd[bdiagoff + d];

              for (k = 0; k < 20; k++)
                if (xvec[x + k] != yvec[x - d + k])
                  break;
              if (k == 20) {
                best = (xlim - bd[bdiagoff + d]) * 2 + dd;
                bestpos = d;
              }
            }
          }
        }
        if (best > 0) {
          cost = 2 * c - 1;
          return bestpos;
        }
      }
    }
  }

  /**
   * Compare in detail contiguous subsequences of the two files
   * which are known, as a whole, to match each other.
   * <p/>
   * The results are recorded in the vectors filevec[N].changed_flag, by
   * storing a 1 in the element for each line that is an insertion or deletion.
   * <p/>
   * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
   * <p/>
   * Note that XLIM, YLIM are exclusive bounds.
   * All line numbers are origin-0 and discarded lines are not counted.
   */

  private void compareseq(int xoff, int xlim, int yoff, int ylim) {
    /* Slide down the bottom initial diagonal. */
    while (xoff < xlim && yoff < ylim && xvec[xoff] == yvec[yoff]) {
      ++xoff;
      ++yoff;
    }
    /* Slide up the top initial diagonal. */
    while (xlim > xoff && ylim > yoff && xvec[xlim - 1] == yvec[ylim - 1]) {
      --xlim;
      --ylim;
    }
    
    /* Handle simple cases. */
    if (xoff == xlim)
      while (yoff < ylim)
        filevec[1].changed_flag[1 + filevec[1].realindexes[yoff++]] = true;
    else if (yoff == ylim)
      while (xoff < xlim)
        filevec[0].changed_flag[1 + filevec[0].realindexes[xoff++]] = true;
    else {
      /* Find a point of correspondence in the middle of the files.  */

      int d = diag(xoff, xlim, yoff, ylim);
      int c = cost;
      int b = bdiag[bdiagoff + d];

      if (c == 1) {
        /* This should be impossible, because it implies that
           one of the two subsequences is empty,
           and that case was handled above without calling `diag'.
           Let's verify that this is true.  */
        throw new IllegalArgumentException("Empty subsequence");
      } else {
        /* Use that point to split this problem into two subproblems.  */
        compareseq(xoff, b, yoff, b - d);
        /* This used to use f instead of b,
           but that is incorrect!
           It is not necessarily the case that diagonal d
           has a snake from b to f.  */
        compareseq(b, xlim, b - d, ylim);
      }
    }
  }

  /**
   * Discard lines from one file that have no matches in the other file.
   */

  private void discard_confusing_lines() {
    filevec[0].discard_confusing_lines(filevec[1]);
    filevec[1].discard_confusing_lines(filevec[0]);
  }

  private boolean inhibit = false;

  /**
   * Adjust inserts/deletes of blank lines to join changes
   * as much as possible.
   */

  private void shift_boundaries() {
    if (inhibit)
      return;
    filevec[0].shift_boundaries(filevec[1]);
    filevec[1].shift_boundaries(filevec[0]);
  }

  public interface ScriptBuilder {
    /**
     * Scan the tables of which lines are inserted and deleted,
     * producing an edit script.
     *
     * @param changed0 true for lines in first file which do not match 2nd
     * @param len0     number of lines in first file
     * @param changed1 true for lines in 2nd file which do not match 1st
     * @param len1     number of lines in 2nd file
     * @return a linked list of changes - or null
     */
    public change build_script(boolean[] changed0, int len0,
                               boolean[] changed1, int len1);
  }

  /**
   * Scan the tables of which lines are inserted and deleted,
   * producing an edit script in reverse order.
   */

  static class ReverseScript implements ScriptBuilder {
    public change build_script(final boolean[] changed0, int len0,
                               final boolean[] changed1, int len1) {
      change script = null;
      int i0 = 0, i1 = 0;
      while (i0 < len0 || i1 < len1) {
        if (changed0[1 + i0] || changed1[1 + i1]) {
          int line0 = i0, line1 = i1;

          /* Find # lines changed here in each file.  */
          while (changed0[1 + i0]) ++i0;
          while (changed1[1 + i1]) ++i1;

          /* Record this change.  */
          script = new change(line0, line1, i0 - line0, i1 - line1, script);
        }

        /* We have reached lines in the two files that match each other.  */
        i0++;
        i1++;
      }

      return script;
    }
  }

  static class ForwardScript implements ScriptBuilder {
    /**
     * Scan the tables of which lines are inserted and deleted,
     * producing an edit script in forward order.
     */
    public change build_script(final boolean[] changed0, int len0,
                               final boolean[] changed1, int len1) {
      change script = null;
      int i0 = len0, i1 = len1;

      while (i0 >= 0 || i1 >= 0) {
        if (changed0[i0] || changed1[i1]) {
          int line0 = i0, line1 = i1;

          /* Find # lines changed here in each file.  */
          while (changed0[i0]) --i0;
          while (changed1[i1]) --i1;

          /* Record this change.  */
          script = new change(i0, i1, line0 - i0, line1 - i1, script);
        }

        /* We have reached lines in the two files that match each other.  */
        i0--;
        i1--;
      }

      return script;
    }
  }

  /**
   * Standard ScriptBuilders.
   */
  public final static ScriptBuilder
    forwardScript = new ForwardScript(),
  reverseScript = new ReverseScript();

  /* Report the differences of two files.  DEPTH is the current directory
     depth. */
  public final change diff_2(final boolean reverse) {
    return diff(reverse ? reverseScript : forwardScript);
  }

  /**
   * Get the results of comparison as an edit script.  The script
   * is described by a list of changes.  The standard ScriptBuilder
   * implementations provide for forward and reverse edit scripts.
   * Alternate implementations could, for instance, list common elements
   * instead of differences.
   *
   * @param bld an object to build the script from change flags
   * @return the head of a list of changes
   */
  public change diff(final ScriptBuilder bld) {

    /* Some lines are obviously insertions or deletions
       because they don't match anything.  Detect them now,
       and avoid even thinking about them in the main comparison algorithm.  */

    discard_confusing_lines();

    /* Now do the main comparison algorithm, considering just the
       undiscarded lines.  */

    xvec = filevec[0].undiscarded;
    yvec = filevec[1].undiscarded;

    int diags =
      filevec[0].nondiscarded_lines + filevec[1].nondiscarded_lines + 3;
    fdiag = new int[diags];
    fdiagoff = filevec[1].nondiscarded_lines + 1;
    bdiag = new int[diags];
    bdiagoff = filevec[1].nondiscarded_lines + 1;

    compareseq(0, filevec[0].nondiscarded_lines,
      0, filevec[1].nondiscarded_lines);
    fdiag = null;
    bdiag = null;

    /* Modify the results slightly to make them prettier
       in cases where that can validly be done.  */

    shift_boundaries();

    /* Get the results of comparison in the form of a chain
       of `struct change's -- an edit script.  */
    return bld.build_script(filevec[0].changed_flag,
      filevec[0].buffered_lines,
      filevec[1].changed_flag,
      filevec[1].buffered_lines);

  }

  /**
   * The result of comparison is an "edit script": a chain of change objects.
   * Each change represents one place where some lines are deleted
   * and some are inserted.
   * <p/>
   * LINE0 and LINE1 are the first affected lines in the two files (origin 0).
   * DELETED is the number of lines deleted here from file 0.
   * INSERTED is the number of lines inserted here in file 1.
   * <p/>
   * If DELETED is 0 then LINE0 is the number of the line before
   * which the insertion was done; vice versa for INSERTED and LINE1.
   */

  public static class change {
    /**
     * Previous or next edit command.
     */
    public change link;
    /**
     * # lines of file 1 changed here.
     */
    public final int inserted;
    /**
     * # lines of file 0 changed here.
     */
    public final int deleted;
    /**
     * Line number of 1st deleted line.
     */
    public final int line0;
    /**
     * Line number of 1st inserted line.
     */
    public final int line1;

    /**
     * Cons an additional entry onto the front of an edit script OLD.
     * LINE0 and LINE1 are the first affected lines in the two files (origin 0).
     * DELETED is the number of lines deleted here from file 0.
     * INSERTED is the number of lines inserted here in file 1.
     * <p/>
     * If DELETED is 0 then LINE0 is the number of the line before
     * which the insertion was done; vice versa for INSERTED and LINE1.
     */
    public change(int line0, int line1, int deleted, int inserted, change old) {
      this.line0 = line0;
      this.line1 = line1;
      this.inserted = inserted;
      this.deleted = deleted;
      this.link = old;
      //System.err.println(line0+","+line1+","+inserted+","+deleted);
    }
  }

  /**
   * Data on one input file being compared.
   */

  class file_data {

    /**
     * Allocate changed array for the results of comparison.
     */
    void clear() {
      /* Allocate a flag for each line of each file, saying whether that line
	 is an insertion or deletion.
	 Allocate an extra element, always zero, at each end of each vector.
       */
      changed_flag = new boolean[buffered_lines + 2];
    }

    /**
     * Return equiv_count[I] as the number of lines in this file
     * that fall in equivalence class I.
     *
     * @return the array of equivalence class counts.
     */
    int[] equivCount() {
      int[] equiv_count = new int[equiv_max];
      for (int i = 0; i < buffered_lines; ++i)
        ++equiv_count[equivs[i]];
      return equiv_count;
    }

    /**
     * Discard lines that have no matches in another file.
     * <p/>
     * A line which is discarded will not be considered by the actual
     * comparison algorithm; it will be as if that line were not in the file.
     * The file's `realindexes' table maps virtual line numbers
     * (which don't count the discarded lines) into real line numbers;
     * this is how the actual comparison algorithm produces results
     * that are comprehensible when the discarded lines are counted.
     * <p/>
     * When we discard a line, we also mark it as a deletion or insertion
     * so that it will be printed in the output.
     *
     * @param f the other file
     */
    void discard_confusing_lines(file_data f) {
      clear();
      /* Set up table of which lines are going to be discarded. */
      final byte[] discarded = discardable(f.equivCount());

      /* Don't really discard the provisional lines except when they occur
         in a run of discardables, with nonprovisionals at the beginning
         and end.  */
      filterDiscards(discarded);

      /* Actually discard the lines. */
      discard(discarded);
    }

    /**
     * Mark to be discarded each line that matches no line of another file.
     * If a line matches many lines, mark it as provisionally discardable.
     *
     * @param counts The count of each equivalence number for the other file.
     * @return 0=nondiscardable, 1=discardable or 2=provisionally discardable
     *         for each line
     */

    private byte[] discardable(final int[] counts) {
      final int end = buffered_lines;
      final byte[] discards = new byte[end];
      final int[] equivs = this.equivs;
      int many = 5;
      int tem = end / 64;

      /* Multiply MANY by approximate square root of number of lines.
	 That is the threshold for provisionally discardable lines.  */
      while ((tem = tem >> 2) > 0)
        many *= 2;

      for (int i = 0; i < end; i++) {
        int nmatch;
        if (equivs[i] == 0)
          continue;
        nmatch = counts[equivs[i]];
        if (nmatch == 0)
          discards[i] = 1;
        else if (nmatch > many)
          discards[i] = 2;
      }
      return discards;
    }

    /**
     * Don't really discard the provisional lines except when they occur
     * in a run of discardables, with nonprovisionals at the beginning
     * and end.
     */

    private void filterDiscards(final byte[] discards) {
      final int end = buffered_lines;

      for (int i = 0; i < end; i++) {
        /* Cancel provisional discards not in middle of run of discards.  */
        if (discards[i] == 2)
          discards[i] = 0;
        else if (discards[i] != 0) {
          /* We have found a nonprovisional discard.  */
          int j;
          int length;
          int provisional = 0;

          /* Find end of this run of discardable lines.
             Count how many are provisionally discardable.  */
          for (j = i; j < end; j++) {
            if (discards[j] == 0)
              break;
            if (discards[j] == 2)
              ++provisional;
          }

          /* Cancel provisional discards at end, and shrink the run.  */
          while (j > i && discards[j - 1] == 2) {
            discards[--j] = 0;
            --provisional;
          }

          /* Now we have the length of a run of discardable lines
             whose first and last are not provisional.  */
          length = j - i;

          /* If 1/4 of the lines in the run are provisional,
             cancel discarding of all provisional lines in the run.  */
          if (provisional * 4 > length) {
            while (j > i)
              if (discards[--j] == 2)
                discards[j] = 0;
          } else {
            int consec;
            int minimum = 1;
            int tem = length / 4;

            /* MINIMUM is approximate square root of LENGTH/4.
               A subrun of two or more provisionals can stand
               when LENGTH is at least 16.
               A subrun of 4 or more can stand when LENGTH >= 64.  */
            while ((tem = tem >> 2) > 0)
              minimum *= 2;
            minimum++;

            /* Cancel any subrun of MINIMUM or more provisionals
               within the larger run.  */
            for (j = 0, consec = 0; j < length; j++)
              if (discards[i + j] != 2)
                consec = 0;
              else if (minimum == ++consec)
              /* Back up to start of subrun, to cancel it all.  */
                j -= consec;
              else if (minimum < consec)
                discards[i + j] = 0;

            /* Scan from beginning of run
               until we find 3 or more nonprovisionals in a row
               or until the first nonprovisional at least 8 lines in.
               Until that point, cancel any provisionals.  */
            for (j = 0, consec = 0; j < length; j++) {
              if (j >= 8 && discards[i + j] == 1)
                break;
              if (discards[i + j] == 2) {
                consec = 0;
                discards[i + j] = 0;
              } else if (discards[i + j] == 0)
                consec = 0;
              else
                consec++;
              if (consec == 3)
                break;
            }

            /* I advances to the last line of the run.  */
            i += length - 1;

            /* Same thing, from end.  */
            for (j = 0, consec = 0; j < length; j++) {
              if (j >= 8 && discards[i - j] == 1)
                break;
              if (discards[i - j] == 2) {
                consec = 0;
                discards[i - j] = 0;
              } else if (discards[i - j] == 0)
                consec = 0;
              else
                consec++;
              if (consec == 3)
                break;
            }
          }
        }
      }
    }

    /**
     * Actually discard the lines.
     *
     * @param discards flags lines to be discarded
     */
    private void discard(final byte[] discards) {
      final int end = buffered_lines;
      int j = 0;
      for (int i = 0; i < end; ++i)
        if (no_discards || discards[i] == 0) {
          undiscarded[j] = equivs[i];
          realindexes[j++] = i;
        } else
          changed_flag[1 + i] = true;
      nondiscarded_lines = j;
    }

    file_data(Object[] data, Hashtable h) {
      buffered_lines = data.length;

      equivs = new int[buffered_lines];
      undiscarded = new int[buffered_lines];
      realindexes = new int[buffered_lines];

      for (int i = 0; i < data.length; ++i) {
        Integer ir = (Integer) h.get(data[i]);
        if (ir == null)
          h.put(data[i], new Integer(equivs[i] = equiv_max++));
        else
          equivs[i] = ir.intValue();
      }
    }

    /**
     * Adjust inserts/deletes of blank lines to join changes
     * as much as possible.
     * <p/>
     * We do something when a run of changed lines include a blank
     * line at one end and have an excluded blank line at the other.
     * We are free to choose which blank line is included.
     * `compareseq' always chooses the one at the beginning,
     * but usually it is cleaner to consider the following blank line
     * to be the "change".  The only exception is if the preceding blank line
     * would join this change to other changes.
     *
     * @param f the file being compared against
     */

    void shift_boundaries(file_data f) {
      final boolean[] changed = changed_flag;
      final boolean[] other_changed = f.changed_flag;
      int i = 0;
      int j = 0;
      int i_end = buffered_lines;
      int preceding = -1;
      int other_preceding = -1;

      for (; ;) {
        int start, end, other_start;

        /* Scan forwards to find beginning of another run of changes.
           Also keep track of the corresponding point in the other file.  */

        while (i < i_end && !changed[1 + i]) {
          while (other_changed[1 + j++])
            /* Non-corresponding lines in the other file
               will count as the preceding batch of changes.  */
            other_preceding = j;
          i++;
        }

        if (i == i_end)
          break;

        start = i;
        other_start = j;

        for (; ;) {
          /* Now find the end of this run of changes.  */

          while (i < i_end && changed[1 + i]) i++;
          end = i;

          /* If the first changed line matches the following unchanged one,
       and this run does not follow right after a previous run,
       and there are no lines deleted from the other file here,
       then classify the first changed line as unchanged
       and the following line as changed in its place.  */

          /* You might ask, how could this run follow right after another?
       Only because the previous run was shifted here.  */

          if (end != i_end
            && equivs[start] == equivs[end]
            && !other_changed[1 + j]
            && end != i_end
            && !((preceding >= 0 && start == preceding)
            || (other_preceding >= 0
            && other_start == other_preceding))) {
            changed[1 + end] = true;
            changed[1 + start++] = false;
            ++i;
            /* Since one line-that-matches is now before this run
               instead of after, we must advance in the other file
               to keep in synch.  */
            ++j;
          } else
            break;
        }

        preceding = i;
        other_preceding = j;
      }
    }

    /**
     * Number of elements (lines) in this file.
     */
    final int buffered_lines;

    /**
     * Vector, indexed by line number, containing an equivalence code for
     * each line.  It is this vector that is actually compared with that
     * of another file to generate differences.
     */
    private final int[] equivs;

    /**
     * Vector, like the previous one except that
     * the elements for discarded lines have been squeezed out.
     */
    final int[] undiscarded;

    /**
     * Vector mapping virtual line numbers (not counting discarded lines)
     * to real ones (counting those lines).  Both are origin-0.
     */
    final int[] realindexes;

    /**
     * Total number of nondiscarded lines.
     */
    int nondiscarded_lines;

    /**
     * Array, indexed by real origin-1 line number,
     * containing true for a line that is an insertion or a deletion.
     * The results of comparison are stored here.
     */
    boolean[] changed_flag;

  }
}

static List<String> diff(Collection<String> a, Collection<String> b) {
  Set<String> set = asSet(b);
  List<String> l = new ArrayList();
  for (String s : a)
    if (!set.contains(s))
      l.add(s);
  return l;
}


static Set asSet(Object[] array) {
  HashSet set = new HashSet();
  for (Object o : array)
    if (o != null)
      set.add(o);
  return set;
}

static Set<String> asSet(String[] array) {
  TreeSet<String> set = new TreeSet();
  for (String o : array)
    if (o != null)
      set.add(o);
  return set;
}

static <A> Set<A> asSet(Collection<A> l) {
  if (l instanceof Set) return (Set) l;
  HashSet<A> set = new HashSet();
  for (A o : l)
    if (o != null)
      set.add(o);
  return set;
}

}