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 CompactHashMap<String, String> map1 = new CompactHashMap();
static HashMap<String, String> map2 = new HashMap();

public static void main(final String[] args) throws Exception {
  check();
  for (int _repeat_0 = 0; _repeat_0 < 100; _repeat_0++)  {
    for (int _repeat_1 = 0; _repeat_1 < 10; _repeat_1++)  {
      putInTwoMaps(map1, map2, aGlobalID(), aGlobalID());
    }
    removeFromTwoMaps(map1, map2, random(keys(map2)));
    check();
  }
  print("OK!");
}

static void check() {
  assertEqualsVerbose(map2.size(), map1.size());
  assertEquals(sorted(keys(map2)), sorted(keys(map1)));
  assertEquals(sorted(values(map2)), sorted(values(map1)));
  for (String key : keys(map1))
    assertEquals(map2.get(key), map1.get(key));
  assertNull(map1.get("unknown"));
}
static String aGlobalID() {
  return randomID(16);
}
static Random random_random = new Random();

static int random(int n) {
  return n <= 0 ? 0 : random_random.nextInt(n);
}

static double random(double max) {
  return random()*max;
}

static double random() {
  return random_random.nextInt(100001)/100000.0;
}

static double random(double min, double max) {
  return min+random()*(max-min);
}

// min <= value < max
static int random(int min, int max) {
  return min+random(max-min);
}

static <A> A random(List<A> l) {
  return oneOf(l);
}

static <A> A random(Collection<A> c) {
  if (c instanceof List) return random((List<A>) c);
  int i = random(l(c));
  return collectionGet(c, i);
}
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<Object> print_byThread; // special handling by thread - prefers F1<S, Bool>

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) {
    Object f = print_byThread.get();
    if (f != null)
      if (isFalse(f instanceof F1 ? ((F1) f).get(s) : callF(f, 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 <A> List<A> sorted(Collection<A> c, final Object comparator) {
  List<A> l = cloneList(c);
  sort(l, makeComparator(comparator));
  return l;
}

static <A> List<A> sorted(Collection<A> c) {
  List<A> l = cloneList(c);
  sort(l);
  return l;
}
static void assertNull(Object a) {
  assertTrue(a == null);
}

static void assertNull(String msg, Object a) {
  assertTrue(msg, a == null);
}
static <A, B> Set<A> keys(Map<A, B> map) {
  return map == null ? new HashSet() : map.keySet();
}

static Set keys(Object map) {
  return keys((Map) map);
}






static <A, B> Collection<B> values(Map<A, B> map) {
  return map == null ? emptyList() : map.values();
}




static Map<Thread, Boolean> _registerThread_threads = newWeakHashMap();

static Thread _registerThread(Thread t) {
  _registerThread_threads.put(t, true);
  return t;
}

static void _registerThread() { _registerThread(Thread.currentThread()); }
static <A, B> void putInTwoMaps(Map<A, B> map1, Map<A, B> map2, A key, B value) {
  map1.put(key, value);
  map2.put(key, value);
}
static void assertEqualsVerbose(Object x, Object y) {
  assertEqualsVerbose((String) null, x, y);
}

static void assertEqualsVerbose(String msg, Object x, Object y) {
  if (!eq(x, y))
    throw fail((msg != null ? msg + ": " : "") + sfu(y) + " != " + sfu(x));
  else
    print("OK: " + sfu(x));
}


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 <A, B> void removeFromTwoMaps(Map<A, B> map1, Map<A, B> map2, A key) {
  map1.remove(key);
  map2.remove(key);
}


static String fixNewLines(String s) {
  return s.replace("\r\n", "\n").replace("\r", "\n");
}
static String sfu(Object o) { return structureForUser(o); }
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 = newWeakHashMap();


// 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(ping_actions) {
      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 WeakHashMap<Class, ArrayList<Method>> callF_cache = new WeakHashMap();




  static <A, B> B callF(F1<A, B> f, A a) {
    return f == null ? null : f.get(a);
  }


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 invokeMethod(methods.get(0), f, args);
  for (int i = 0; i < n; i++) {
    Method m = methods.get(i);
    if (call_checkArgs(m, args, false))
      return invokeMethod(m, 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, B> Map<A, B> newWeakHashMap() {
  return _registerWeakMap(synchroMap(new WeakHashMap()));
}
static <A> A oneOf(List<A> l) {
  return l.isEmpty() ? null : l.get(new Random().nextInt(l.size()));
}

static char oneOf(String s) {
  return empty(s) ? '?' : s.charAt(random(l(s)));
}

static String oneOf(String... l) {
  return oneOf(asList(l));
}
static List emptyList() {
  return new ArrayList();
  //ret Collections.emptyList();
}

static List emptyList(int capacity) {
  return new ArrayList(capacity);
}

// Try to match capacity
static List emptyList(Iterable l) {
  return l instanceof Collection ? emptyList(((Collection) l).size()) : emptyList();
}
static <A> A collectionGet(Collection<A> c, int idx) {
  if (c == null || idx < 0 || idx >= l(c)) return null;
  if (c instanceof List) return listGet((List<A>) c, idx);
  Iterator<A> it = c.iterator();
  for (int i = 0; i < idx; i++) if (it.hasNext()) it.next(); else return null;
  return it.hasNext() ? it.next() : null;
}
static void assertTrue(Object o) {
  if (!(eq(o, true) /*|| isTrue(pcallF(o))*/))
    throw fail(str(o));
}
  
static boolean assertTrue(String msg, boolean b) {
  if (!b)
    throw fail(msg);
  return b;
}

static boolean assertTrue(boolean b) {
  if (!b)
    throw fail("oops");
  return b;
}
static <A> ArrayList<A> cloneList(Collection<A> l) {
  if (l == null) return new ArrayList();
  // TODO: is this correct when l is a keySet?
  synchronized(l) {
    return new ArrayList<A>(l);
  }
}
static boolean isFalse(Object o) {
  return eq(false, o);
}
static <T> void sort(T[] a, Comparator<? super T> c) {
  Arrays.sort(a, c);
}

static <T> void sort(T[] a) {
  Arrays.sort(a);
}

static <T> void sort(List<T> a, Comparator<? super T> c) {
  Collections.sort(a, c);
}

static void sort(List a) {
  Collections.sort(a);
}
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 Comparator makeComparator(final Object f) {
  if (f instanceof Comparator) return (Comparator) f;
  return new Comparator() {
    public int compare(Object a, Object b) {
      return (int) callF(f, a, b);
    }
  };
}

static boolean eq(Object a, Object b) {
  return a == null ? b == null : a == b || a.equals(b);
}

// a little kludge for stuff like eq(symbol, "$X")

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(msg == null ? "" : msg); }
static RuntimeException fail(String msg, Throwable innerException) { throw new RuntimeException(msg, innerException); }

static int randomID_defaultLength = 12;

static String randomID(int length) {
  return makeRandomID(length);
}

static String randomID() {
  return randomID(randomID_defaultLength);
}
static <A> List<A> concatLists(Collection<A>... lists) {
  List<A> l = new ArrayList();
  for (Collection<A> list : lists)
    if (list != null)
      l.addAll(list);
  return l;
}

static <A> List<A> concatLists(Collection<? extends Collection<A>> lists) {
  List<A> l = new ArrayList();
  for (Collection<A> list : lists)
    if (list != null)
      l.addAll(list);
  return l;
}



static Map synchroMap() {
  return synchroHashMap();
}

static <A, B> Map<A, B> synchroMap(Map<A, B> map) {
  return Collections.synchronizedMap(map);
}
static <A> A listGet(List<A> l, int idx) {
  return l != null && idx >= 0 && idx < l(l) ? l.get(idx) : null;
}
static 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;
  if (callMC_cache == null) callMC_cache = new HashMap(); // initializer time workaround
  synchronized(callMC_cache) {
    me = method == callMC_key ? callMC_value : null;
  }
  if (me != null) try {
    return invokeMethod(me, null, args);
  } catch (IllegalArgumentException e) {
    throw new RuntimeException("Can't call " + me + " with arguments " + classNames(args), e);
  }

  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;
    }
    try {
      return invokeMethod(me, null, args);
    } catch (IllegalArgumentException e) {
      throw new RuntimeException("Can't call " + me + " with arguments " + classNames(args), e);
    }
  }
  for (int i = 0; i < n; i++) {
    me = m.get(i);
    if (call_checkArgs(me, args, false))
      return invokeMethod(me, 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() & java.lang.reflect.Modifier.STATIC) != 0) {
          m.setAccessible(true);
          multiMapPut(callMC_cache, m.getName(), m);
        }
      c = c.getSuperclass();
    }
  }
}
static <A> ArrayList<A> asList(A[] a) {
  return a == null ? new ArrayList<A>() : 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;
}
static boolean empty(Collection c) { return c == null || c.isEmpty(); }
static boolean empty(String s) { return s == null || s.length() == 0; }
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);
  if (o == null) return true;
  throw fail("unknown type for 'empty': " + getType(o));
}

static boolean empty(float[] a) { return a == null || a.length == 0; }
static boolean empty(int[] a) { return a == null || a.length == 0; }
static boolean empty(long[] a) { return a == null || a.length == 0; }
static RuntimeException asRuntimeException(Throwable t) {
  
  if (t instanceof Error)
    _handleError((Error) t);
  
  return t instanceof RuntimeException ? (RuntimeException) t : new RuntimeException(t);
}
static String structureForUser(Object o) {
  return beautifyStructure(struct_noStringSharing(o));
}
// 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 RuntimeException rethrow(Throwable e) {
  throw asRuntimeException(e);
}
static Thread currentThread() {
  return Thread.currentThread();
}
static String makeRandomID(int length) {
  Random random = new Random();
  char[] id = new char[length];
  for (int i = 0; i < id.length; i++)
    id[i] = (char) ((int) 'a' + random.nextInt(26));
  return new String(id);
}
static String str(Object o) {
  return o == null ? "null" : o.toString();
}

static String str(char[] c) {
  return new String(c);
}
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 invokeMethod(m, null, args);
    } else {
      Method m = call_findMethod(o, method, args, false);
      m.setAccessible(true);
      return invokeMethod(m, 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() & java.lang.reflect.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 List _registerWeakMap_preList;

static <A> A _registerWeakMap(A map) {
  if (javax() == null) {
    // We're in class init
    if (_registerWeakMap_preList == null) _registerWeakMap_preList = synchroList();
    _registerWeakMap_preList.add(map);
    return map;
  }
  
  try {
    call(javax(), "_registerWeakMap", map);
  } catch (Throwable e) {
    printException(e);
    print("Upgrade JavaX!!");
  }
  return map;
}

static void _onLoad_registerWeakMap() {
  assertNotNull(javax());
  if (_registerWeakMap_preList == null) return;
  for (Object o : _registerWeakMap_preList)
    _registerWeakMap(o);
  _registerWeakMap_preList = null;
}
static String getClassName(Object o) {
  return o == null ? "null" : o instanceof Class ? ((Class) o).getName() : o.getClass().getName();
}
static Object invokeMethod(Method m, Object o, Object... args) { try {
  try {
    return m.invoke(o, args);
  } catch (InvocationTargetException e) {
    throw rethrow(getExceptionCause(e));
  }
} catch (Exception __e) { throw rethrow(__e); } }


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 AtomicLong _handleError_nonVMErrors = new AtomicLong();
static AtomicLong _handleError_vmErrors = new AtomicLong();
static AtomicLong _handleError_outOfMemoryErrors = new AtomicLong();
static volatile long _handleError_lastOutOfMemoryError;
static volatile Error _handleError_lastHardError;

static void _handleError(Error e) {
  if (!(e instanceof VirtualMachineError)) {
    incAtomicLong(_handleError_nonVMErrors);
    return;
  }
  
  print("\nHARD ERROR\n");
  printStackTrace2(e);
  print("\nHARD ERROR\n");
  _handleError_lastHardError = e;
  
  incAtomicLong(_handleError_vmErrors);
  if (e instanceof OutOfMemoryError) {
    incAtomicLong(_handleError_outOfMemoryErrors);
    _handleError_lastOutOfMemoryError = sysNow();
  }
}
static String struct_noStringSharing(Object o) {
  structure_Data d = new structure_Data();
  d.noStringSharing = true;
  return structure(o, d);
}
static Throwable getExceptionCause(Throwable e) {
  Throwable c = e.getCause();
  return c != null ? c : e;
}
static Object callFunction(Object f, Object... args) {
  return callF(f, args);
}
static List<String> classNames(Collection l) {
  return getClassNames(l);
}

static List<String> classNames(Object[] l) {
  return getClassNames(Arrays.asList(l));
}
static Class javax() {
  return getJavaX();
}
static Class mc() {
  return main.class;
}
static <A> A assertNotNull(A a) {
  assertTrue(a != null);
  return a;
}

static <A> A assertNotNull(String msg, A a) {
  assertTrue(msg, a != null);
  return a;
}
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);
}
// 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 void printException(Throwable e) {
  printStackTrace(e);
}
static String getType(Object o) {
  return getClassName(o);
}
static String beautifyStructure(String s) {
  return structure_addTokenMarkers(s);
}
static <A> List<A> synchroList() {
  return Collections.synchronizedList(new ArrayList<A>());
}

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

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

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 structure_addTokenMarkers(String s) {
  List<String> tok = javaTok(s);
  
  // find references
  
  TreeSet<Integer> refs = new TreeSet();
  for (int i = 1; i < l(tok); i += 2) {
    String t = tok.get(i);
    if (t.startsWith("t") && isInteger(t.substring(1)))
      refs.add(parseInt(t.substring(1)));
  }
  
  if (empty(refs)) return s;
  
  // add markers
  for (int i : refs) {
    int idx = i*2+1;
    String t = "";
    if (endsWithLetterOrDigit(tok.get(idx-1))) t = " ";
    tok.set(idx, t + "m" + i + " " + tok.get(idx));
  }
  
  return join(tok);
}
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(S indent, Throwable e) {
  if (endsWithLetter(indent)) indent += " ";
  printIndent(indent, getStackTrace(e));
}*/
static long sysNow() {
  return System.nanoTime()/1000000;
}
static void incAtomicLong(AtomicLong l) {
  l.incrementAndGet();
}
static List<String> getClassNames(Collection l) {
  List<String> out = new ArrayList();
  if (l != null) for (Object o : l)
    out.add(o == null ? null : getClassName(o));
  return out;
}
static Class __javax;

static Class getJavaX() {
  return __javax;
}
static boolean structure_showTiming, structure_checkTokenCount;

static String structure(Object o) {
  return structure(o, new structure_Data());
}

static String structure(Object o, structure_Data d) {
  StringWriter sw = new StringWriter();
  d.out = new PrintWriter(sw);
  structure_go(o, d);
  String s = str(sw);
  if (structure_checkTokenCount) {
    print("token count=" + d.n);
    assertEquals("token count", l(javaTokC(s)), d.n);
  }
  return s;
}

static void structure_go(Object o, structure_Data d) {
  structure_1(o, d);
  while (nempty(d.stack))
    popLast(d.stack).run();
}

static void structureToPrintWriter(Object o, PrintWriter out) {
  structure_Data d = new structure_Data();
  d.out = out;
  structure_go(o, d);
}

// leave to false, unless unstructure() breaks
static boolean structure_allowShortening = false;

static class structure_Data {
  PrintWriter out;
  int stringSizeLimit;
  int shareStringsLongerThan = 20;
  boolean noStringSharing;

  IdentityHashMap<Object,Integer> seen = new IdentityHashMap();
  //new BitSet refd;
  HashMap<String,Integer> strings = new HashMap();
  HashSet<String> concepts = new HashSet();
  HashMap<Class, List<Field>> fieldsByClass = new HashMap();
  int n; // token count
  List<Runnable> stack = new ArrayList();
  
  // append single token
  structure_Data append(String token) { out.print(token); ++n; return this; }
  structure_Data append(int i) { out.print(i); ++n; return this; }
  
  // append multiple tokens
  structure_Data append(String token, int tokCount) { out.print(token); n += tokCount; return this; }
  
  // extend last token
  structure_Data app(String token) { out.print(token); return this; }
  structure_Data app(int i) { out.print(i); return this; }
}

static void structure_1(final Object o, final structure_Data d) {
  if (o == null) { d.append("null"); return; }
  
  Class c = o.getClass();
  boolean concept = false;
  
  List<Field> lFields = d.fieldsByClass.get(c);
  
  if (lFields == null) {
    // these are never back-referenced (for readability)
    
    if (o instanceof Number) {
      PrintWriter out = d.out;
if (o instanceof Integer) { int i = ((Integer) o).intValue(); out.print(i); d.n += i < 0 ? 2 : 1; return; }
      if (o instanceof Long) { long l = ((Long) o).longValue(); out.print(l); out.print("L"); d.n += l < 0 ? 2 : 1; return; }
      if (o instanceof Short) { short s = ((Short) o).shortValue(); d.append("sh ", 2); out.print(s); d.n += s < 0 ? 2 : 1; return; }
      if (o instanceof Float) { d.append("fl ", 2); quoteToPrintWriter(str(o), out); return; }
      if (o instanceof Double) { d.append("d(", 3); quoteToPrintWriter(str(o), out); d.append(")"); return; }
      if (o instanceof BigInteger) { out.print("bigint("); out.print(o); out.print(")"); d.n += ((BigInteger) o).signum() < 0 ? 5 : 4; return; }
    }
  
    if (o instanceof Boolean) {
      d.append(((Boolean) o).booleanValue() ? "t" : "f"); return;
    }
      
    if (o instanceof Character) {
      d.append(quoteCharacter((Character) o)); return;
    }
      
    if (o instanceof File) {
      d.append("File ").append(quote(((File) o).getPath())); return;
    }
      
    // referencable objects follow
    
    Integer ref = d.seen.get(o);
    if (o instanceof String && ref == null) ref = d.strings.get((String) o);
    if (ref != null) { /*d.refd.set(ref);*/ d.append("t").app(ref); return; }

    if (!(o instanceof String))
      d.seen.put(o, d.n); // record token number
    else {
      String s = d.stringSizeLimit != 0 ? shorten((String) o, d.stringSizeLimit) : (String) o;
      if (!d.noStringSharing) {
        if (d.shareStringsLongerThan == Integer.MAX_VALUE)
          d.seen.put(o, d.n);
        if (l(s) >= d.shareStringsLongerThan)
          d.strings.put(s, d.n);
      }
      quoteToPrintWriter(s, d.out); d.n++; return;
    }
      
    if (o instanceof HashSet) {
      d.append("hashset ");
      structure_1(new ArrayList((Set) o), d);
      return;
    }
  
    if (o instanceof TreeSet) {
      d.append("treeset ");
      structure_1(new ArrayList((Set) o), d);
      return;
    }
    
    String name = c.getName();
    if (o instanceof Collection
      && !startsWith(name, "main$")
      /* && neq(name, "main$Concept$RefL") */) {
      d.append("[");
      final int l = d.n;
      final Iterator it = ((Collection) o).iterator();
      d.stack.add(new Runnable() { public void run() { try { 
        if (!it.hasNext())
          d.append("]");
        else {
          d.stack.add(this);
          if (d.n != l) d.append(", ");
          structure_1(it.next(), d);
        }
      
} catch (Exception __e) { throw rethrow(__e); } }  public String toString() { return "if (!it.hasNext())\r\n          d.append(\"]\");\r\n        else {\r\n          d.sta..."; }});
      return;
    }
    
    if (o instanceof Map && !startsWith(name, "main$")) {
      if (o instanceof LinkedHashMap) d.append("lhm");
      else if (o instanceof HashMap) d.append("hm");
      d.append("{");
      final int l = d.n;
      final Iterator it = ((Map) o).entrySet().iterator();
      
      d.stack.add(new Runnable() {
        boolean v;
        Map.Entry e;
        
        public void run() {
          if (v) {
            d.append("=");
            v = false;
            d.stack.add(this);
            structure_1(e.getValue(), d);
          } else {
            if (!it.hasNext())
              d.append("}");
            else {
              e = (Map.Entry) it.next();
              v = true;
              d.stack.add(this);
              if (d.n != l) d.append(", ");
              structure_1(e.getKey(), d);
            }
          }
        }
      });
      return;
    }
    
    if (c.isArray()) {
      if (o instanceof byte[]) {
        d.append("ba ").append(quote(bytesToHex((byte[]) o))); return;
      }
  
      final int n = Array.getLength(o);
  
      if (o instanceof boolean[]) {
        String hex = boolArrayToHex((boolean[]) o);
        int i = l(hex);
        while (i > 0 && hex.charAt(i-1) == '0' && hex.charAt(i-2) == '0') i -= 2;
        d.append("boolarray ").append(n).app(" ").append(quote(substring(hex, 0, i))); return;
      }
      
      String atype = "array", sep = ", ";
  
      if (o instanceof int[]) {
        //ret "intarray " + quote(intArrayToHex((int[]) o));
        atype = "intarray";
        sep = " ";
      }
      
      d.append(atype).append("{");
      d.stack.add(new Runnable() {
        int i;
        public void run() {
          if (i >= n)
            d.append("}");
          else {
            d.stack.add(this);
            if (i > 0) d.append(", ");
            structure_1(Array.get(o, i++), d);
          }
        }
      });
      return;
    }
  
    if (o instanceof Class) {
      d.append("class(", 2).append(quote(((Class) o).getName())).append(")"); return;
    }
      
    if (o instanceof Throwable) {
      d.append("exception(", 2).append(quote(((Throwable) o).getMessage())).append(")"); return;
    }
      
    if (o instanceof BitSet) {
      BitSet bs = (BitSet) o;
      d.append("bitset{", 2);
      int l = d.n;
      for (int i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) {
        if (d.n != l) d.append(", ");
        d.append(i);
      }
      d.append("}"); return;
    }
      
    // Need more cases? This should cover all library classes...
    if (name.startsWith("java.") || name.startsWith("javax.")) {
      d.append("j ").append(quote(str(o))); return; // Hm. this is not unstructure-able
    }
    
    
      
    /*if (name.equals("main$Lisp")) {
      fail("lisp not supported right now");
    }*/
    
    String dynName = shortDynamicClassName(o);
    if (concept && !d.concepts.contains(dynName)) {
      d.concepts.add(dynName);
      d.append("c ");
    }
    
    // serialize an object with fields.
    // first, collect all fields and values in fv.
    
    TreeSet<Field> fields = new TreeSet<Field>(new Comparator<Field>() {
      public int compare(Field a, Field b) {
        return stdcompare(a.getName(), b.getName());
      }
    });
    
    Class cc = c;
    while (cc != Object.class) {
      for (Field field : getDeclaredFields_cached(cc)) {
        if ((field.getModifiers() & (java.lang.reflect.Modifier.STATIC | java.lang.reflect.Modifier.TRANSIENT)) != 0)
          continue;
        String fieldName = field.getName();
        
        fields.add(field);
        
        // put special cases here...
      }
        
      cc = cc.getSuperclass();
    }
    
    lFields = asList(fields);
    
    // Render this$1 first because unstructure needs it for constructor call.
    
    for (int i = 0; i < l(lFields); i++) {
      Field f = lFields.get(i);
      if (f.getName().equals("this$1")) {
        lFields.remove(i);
        lFields.add(0, f);
        break;
      }
    }
  
    
    d.fieldsByClass.put(c, lFields);
  } // << if (lFields == null)
  else { // ref handling for lFields != null
    Integer ref = d.seen.get(o);
    if (ref != null) { /*d.refd.set(ref);*/ d.append("t").app(ref); return; }
    d.seen.put(o, d.n); // record token number
  }

  LinkedHashMap<String,Object> fv = new LinkedHashMap();
  for (Field f : lFields) {
    Object value;
    try {
      value = f.get(o);
    } catch (Exception e) {
      value = "?";
    }
      
    if (value != null)
      fv.put(f.getName(), value);
    
  }
  
  String name = c.getName();
  String shortName = dropPrefix("main$", name);
    
  // Now we have fields & values. Process fieldValues if it's a DynamicObject.
  
  // omit field "className" if equal to class's name
  if (concept && eq(fv.get("className"), shortName))
    fv.remove("className");
          
  if (o instanceof DynamicObject) {
    fv.putAll((Map) fv.get("fieldValues"));
    fv.remove("fieldValues");
    shortName = shortDynamicClassName(o);
    fv.remove("className");
  }
  
  String singleField = fv.size() == 1 ? first(fv.keySet()) : null;
  
  d.append(shortName);
  
  
  final int l = d.n;
  final Iterator it = fv.entrySet().iterator();
  
  d.stack.add(new Runnable() { public void run() { try { 
    if (!it.hasNext()) {
      if (d.n != l)
        d.append(")");
    } else {
      Map.Entry e = (Map.Entry) it.next();
      d.append(d.n == l ? "(" : ", ");
      d.append((String) e.getKey()).append("=");
      d.stack.add(this);
      structure_1(e.getValue(), d);
    }
  
} catch (Exception __e) { throw rethrow(__e); } }  public String toString() { return "if (!it.hasNext()) {\r\n      if (d.n != l)\r\n        d.append(\")\");\r\n    } else..."; }});
}

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(S indent, Throwable e) {
  if (endsWithLetter(indent)) indent += " ";
  printIndent(indent, getStackTrace2(e));
}*/


static String quote(Object o) {
  if (o == null) return "null";
  return quote(str(o));
}

static String quote(String s) {
  if (s == null) return "null";
  StringBuilder out = new StringBuilder((int) (l(s)*1.5+2));
  quote_impl(s, out);
  return out.toString();
}
  
static void quote_impl(String s, StringBuilder out) {
  out.append('"');
  int l = s.length();
  for (int i = 0; i < l; i++) {
    char c = s.charAt(i);
    if (c == '\\' || c == '"')
      out.append('\\').append(c);
    else if (c == '\r')
      out.append("\\r");
    else if (c == '\n')
      out.append("\\n");
    else
      out.append(c);
  }
  out.append('"');
}
static int shorten_default = 100;

static String shorten(String s) { return shorten(s, shorten_default); }

static String shorten(String s, int max) {
  return shorten(s, max, "...");
}

static String shorten(String s, int max, String shortener) {
  if (s == null) return "";
  if (max < 0) return s;
  return s.length() <= max ? s : substring(s, 0, min(s.length(), max-l(shortener))) + shortener;
}

static String shorten(int max, String s) { return shorten(s, max); }
static String quoteCharacter(char c) {
  if (c == '\'') return "'\\''";
  if (c == '\\') return "'\\\\'";
  if (c == '\r') return "'\\r'";
  if (c == '\n') return "'\\n'";
  if (c == '\t') return "'\\t'";
  return "'" + c + "'";
}

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));
}

static String join(Iterable<String> strings) {
  return join("", strings);
}

static String join(Iterable<String> strings, String glue) {
  return join(glue, strings);
}

public static String join(String[] strings) {
  return join("", strings);
}


static String getStackTrace2(Throwable throwable) {
  return hideCredentials(getStackTrace(throwable) + replacePrefix("java.lang.RuntimeException: ", "FAIL: ",
    hideCredentials(str(getInnerException(throwable)))) + "\n");
}
static String shortDynamicClassName(Object o) {
 if (o instanceof DynamicObject && ((DynamicObject) o).className != null)
    return ((DynamicObject) o).className;
  return shortClassName(o);
}
static String dropPrefix(String prefix, String s) {
  return s == null ? null : s.startsWith(prefix) ? s.substring(l(prefix)) : s;
}
// replacement for class JavaTok
// maybe incomplete, might want to add floating point numbers
// todo also: extended multi-line strings

static int javaTok_n, javaTok_elements;
static boolean javaTok_opt;

static List<String> javaTok(String s) {
  return javaTok(s, null);
}

static List<String> javaTok(String s, List<String> existing) {
  ++javaTok_n;
  int nExisting = javaTok_opt && existing != null ? existing.size() : 0;
  ArrayList<String> tok = existing != null ? new ArrayList(nExisting) : new ArrayList();
  int l = s.length();
  
  int i = 0, n = 0;
  while (i < l) {
    int j = i;
    char c, d;
    
    // scan for whitespace
    while (j < l) {
      c = s.charAt(j);
      d = j+1 >= l ? '\0' : s.charAt(j+1);
      if (c == ' ' || c == '\t' || c == '\r' || c == '\n')
        ++j;
      else if (c == '/' && d == '*') {
        do ++j; while (j < l && !s.substring(j, Math.min(j+2, l)).equals("*/"));
        j = Math.min(j+2, l);
      } else if (c == '/' && d == '/') {
        do ++j; while (j < l && "\r\n".indexOf(s.charAt(j)) < 0);
      } else
        break;
    }
    
    if (n < nExisting && javaTok_isCopyable(existing.get(n), s, i, j))
      tok.add(existing.get(n));
    else
      tok.add(javaTok_substringN(s, i, j));
    ++n;
    i = j;
    if (i >= l) break;
    c = s.charAt(i);
    d = i+1 >= l ? '\0' : s.charAt(i+1);

    // scan for non-whitespace
    
    // Special JavaX syntax: 'identifier
    if (c == '\'' && Character.isJavaIdentifierStart(d) && i+2 < l && "'\\".indexOf(s.charAt(i+2)) < 0) {
      j += 2;
      while (j < l && Character.isJavaIdentifierPart(s.charAt(j)))
        ++j;
    } else if (c == '\'' || c == '"') {
      char opener = c;
      ++j;
      while (j < l) {
        if (s.charAt(j) == opener /*|| s.charAt(j) == '\n'*/) { // allow multi-line strings
          ++j;
          break;
        } else if (s.charAt(j) == '\\' && j+1 < l)
          j += 2;
        else
          ++j;
      }
    } else if (Character.isJavaIdentifierStart(c))
      do ++j; while (j < l && (Character.isJavaIdentifierPart(s.charAt(j)) || "'".indexOf(s.charAt(j)) >= 0)); // for stuff like "don't"
    else if (Character.isDigit(c)) {
      do ++j; while (j < l && Character.isDigit(s.charAt(j)));
      if (j < l && s.charAt(j) == 'L') ++j; // Long constants like 1L
    } else if (c == '[' && d == '[') {
      do ++j; while (j+1 < l && !s.substring(j, j+2).equals("]]"));
      j = Math.min(j+2, l);
    } else if (c == '[' && d == '=' && i+2 < l && s.charAt(i+2) == '[') {
      do ++j; while (j+2 < l && !s.substring(j, j+3).equals("]=]"));
      j = Math.min(j+3, l);
    } else
      ++j;
      
    if (n < nExisting && javaTok_isCopyable(existing.get(n), s, i, j))
      tok.add(existing.get(n));
    else
      tok.add(javaTok_substringC(s, i, j));
    ++n;
    i = j;
  }
  
  if ((tok.size() % 2) == 0) tok.add("");
  javaTok_elements += tok.size();
  return tok;
}

static List<String> javaTok(List<String> tok) {
  return javaTok(join(tok), tok);
}

static boolean javaTok_isCopyable(String t, String s, int i, int j) {
  return t.length() == j-i
    && s.regionMatches(i, t, 0, j-i); // << could be left out, but that's brave
}
static List<String> javaTokC(String s) {
  if (s == null) return null;
  int l = s.length();
  ArrayList<String> tok = new ArrayList();
  
  int i = 0;
  while (i < l) {
    int j = i;
    char c, d;
    
    // scan for whitespace
    while (j < l) {
      c = s.charAt(j);
      d = j+1 >= l ? '\0' : s.charAt(j+1);
      if (c == ' ' || c == '\t' || c == '\r' || c == '\n')
        ++j;
      else if (c == '/' && d == '*') {
        do ++j; while (j < l && !s.substring(j, Math.min(j+2, l)).equals("*/"));
        j = Math.min(j+2, l);
      } else if (c == '/' && d == '/') {
        do ++j; while (j < l && "\r\n".indexOf(s.charAt(j)) < 0);
      } else
        break;
    }
    
    i = j;
    if (i >= l) break;
    c = s.charAt(i);
    d = i+1 >= l ? '\0' : s.charAt(i+1);

    // scan for non-whitespace
    if (c == '\'' || c == '"') {
      char opener = c;
      ++j;
      while (j < l) {
        if (s.charAt(j) == opener || s.charAt(j) == '\n') { // end at \n to not propagate unclosed string literal errors
          ++j;
          break;
        } else if (s.charAt(j) == '\\' && j+1 < l)
          j += 2;
        else
          ++j;
      }
    } else if (Character.isJavaIdentifierStart(c))
      do ++j; while (j < l && (Character.isJavaIdentifierPart(s.charAt(j)) || "'".indexOf(s.charAt(j)) >= 0)); // for stuff like "don't"
    else if (Character.isDigit(c)) {
      do ++j; while (j < l && Character.isDigit(s.charAt(j)));
      if (j < l && s.charAt(j) == 'L') ++j; // Long constants like 1L
    } else if (c == '[' && d == '[') {
      do ++j; while (j+1 < l && !s.substring(j, j+2).equals("]]"));
      j = Math.min(j+2, l);
    } else if (c == '[' && d == '=' && i+2 < l && s.charAt(i+2) == '[') {
      do ++j; while (j+2 < l && !s.substring(j, j+3).equals("]=]"));
      j = Math.min(j+3, l);
    } else
      ++j;
      
    tok.add(javaTok_substringC(s, i, j));
    i = j;
  }
  
  return tok;
}
static HashMap<Class, Field[]> getDeclaredFields_cache = new HashMap();

static Field[] getDeclaredFields_cached(Class c) {
  Field[] fields;
  synchronized(getDeclaredFields_cache) {
    fields = getDeclaredFields_cache.get(c);
    if (fields == null) {
      getDeclaredFields_cache.put(c, fields = c.getDeclaredFields());
      for (Field f : fields)
        f.setAccessible(true);
    }
  }
  return fields;
}
static String boolArrayToHex(boolean[] a) {
  return bytesToHex(boolArrayToBytes(a));
}
static boolean endsWithLetterOrDigit(String s) {
  return nempty(s) && isLetterOrDigit(lastCharacter(s));
}
static Object first(Object list) {
  return empty((List) list) ? null : ((List) list).get(0);
}

static <A> A first(List<A> list) {
  return empty(list) ? null : list.get(0);
}

static <A> A first(A[] bla) {
  return bla == null || bla.length == 0 ? null : bla[0];
}

static <A> A first(Iterable<A> i) {
  if (i == null) return null;
  Iterator<A> it = i.iterator();
  return it.hasNext() ? it.next() : null;
}

static Character first(String s) { return empty(s) ? null : s.charAt(0); }


static Iterator emptyIterator() {
  return Collections.emptyIterator();
}
  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 boolean isInteger(String s) {
  if (s == null) return false;
  int n = l(s);
  if (n == 0) return false;
  int i = 0;
  if (s.charAt(0) == '-')
    if (++i >= n) return false;
  while (i < n) {
    char c = s.charAt(i);
    if (c < '0' || c > '9') return false;
    ++i;
  }
  return true;
}
static String getStackTrace(Throwable throwable) {
  lastException(throwable);
  return getStackTrace_noRecord(throwable);
}

static String getStackTrace_noRecord(Throwable throwable) {
  StringWriter writer = new StringWriter();
  throwable.printStackTrace(new PrintWriter(writer));
  return hideCredentials(writer.toString());
}

static String getStackTrace() {
  return getStackTrace_noRecord(new Throwable());
}
static void quoteToPrintWriter(String s, PrintWriter out) {
  if (s == null) { out.print("null"); return; }
  out.print('"');
  int l = s.length();
  for (int i = 0; i < l; i++) {
    char c = s.charAt(i);
    if (c == '\\' || c == '"') {
      out.print('\\'); out.print(c);
    } else if (c == '\r')
      out.print("\\r");
    else if (c == '\n')
      out.print("\\n");
    else
      out.print(c);
  }
  out.print('"');
}
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 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 int parseInt(String s) {
  return empty(s) ? 0 : Integer.parseInt(s);
}

static int parseInt(char c) {
  return Integer.parseInt(str(c));
}
static <A> A popLast(List<A> l) {
  return liftLast(l);
}
static int stdcompare(Number a, Number b) {
  return cmp(a, b);
}

static int stdcompare(String a, String b) {
  return cmp(a, b);
}

static int stdcompare(long a, long b) {
  return a < b ? -1 : a > b ? 1 : 0;
}

static int stdcompare(Object a, Object b) {
  return cmp(a, b);
}

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

static boolean startsWith(String a, char c) {
  return nempty(a) && a.charAt(0) == c;
}



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 volatile Throwable lastException_lastException;

static Throwable lastException() {
  return lastException_lastException;
}

static void lastException(Throwable e) {
  lastException_lastException = e;
}
static String javaTok_substringC(String s, int i, int j) {
  return s.substring(i, j);
}
static String javaTok_substringN(String s, int i, int j) {
  if (i == j) return "";
  if (j == i+1 && s.charAt(i) == ' ') return " ";
  return s.substring(i, j);
}
static byte[] boolArrayToBytes(boolean[] a) {
  byte[] b = new byte[(l(a)+7)/8];
  for (int i = 0; i < l(a); i++)
    if (a[i])
      b[i/8] |= 1 << (i & 7);
  return b;
}
static String replacePrefix(String prefix, String replacement, String s) {
  if (!startsWith(s, prefix)) return s;
  return replacement + substring(s, l(prefix));
}
static <A> A liftLast(List<A> l) {
  if (l.isEmpty()) return null;
  int i = l(l)-1;
  A a = l.get(i);
  l.remove(i);
  return a;
}
static int cmp(Number a, Number b) {
  return a == null ? b == null ? 0 : -1 : cmp(a.doubleValue(), b.doubleValue());
}

static int cmp(double a, double b) {
  return a < b ? -1 : a == b ? 0 : 1;
}

static int cmp(String a, String b) {
  return a == null ? b == null ? 0 : -1 : a.compareTo(b);
}

static int cmp(Object a, Object b) {
  if (a == null) return b == null ? 0 : -1;
  if (b == null) return 1;
  return ((Comparable) a).compareTo(b);
}
static int min(int a, int b) {
  return Math.min(a, b);
}

static long min(long a, long b) {
  return Math.min(a, b);
}

static float min(float a, float b) { return Math.min(a, b); }
static float min(float a, float b, float c) { return min(min(a, b), c); }

static double min(double a, double b) {
  return Math.min(a, b);
}

static double min(double[] c) {
  double x = Double.MAX_VALUE;
  for (double d : c) x = Math.min(x, d);
  return x;
}

static float min(float[] c) {
  float x = Float.MAX_VALUE;
  for (float d : c) x = Math.min(x, d);
  return x;
}

static byte min(byte[] c) {
  byte x = 127;
  for (byte d : c) if (d < x) x = d;
  return x;
}

static short min(short[] c) {
  short x = 0x7FFF;
  for (short d : c) if (d < x) x = d;
  return x;
}
static String hideCredentials(URL url) { return url == null ? null : hideCredentials(str(url)); }

static String hideCredentials(String url) {
  return url.replaceAll("([&?])_pass=[^&\\s\"]*", "$1_pass=<hidden>");
}
static Throwable getInnerException(Throwable e) {
  while (e.getCause() != null)
    e = e.getCause();
  return e;
}
static char lastCharacter(String s) {
  return empty(s) ? 0 : s.charAt(l(s)-1);
}
static boolean neq(Object a, Object b) {
  return !eq(a, b);
}
static boolean isLetterOrDigit(char c) {
  return Character.isLetterOrDigit(c);
}
static String shortClassName(Object o) {
  if (o == null) return null;
  Class c = o instanceof Class ? (Class) o : o.getClass();
  String name = c.getName();
  return shortenClassName(name);
}
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 shortenClassName(String name) {
  if (name == null) return null;
  int i = lastIndexOf(name, "$");
  if (i < 0) i = lastIndexOf(name, ".");
  return i < 0 ? name : substring(name, i+1);
}


static int lastIndexOf(String a, String b) {
  return a == null || b == null ? -1 : a.lastIndexOf(b);
}

static int lastIndexOf(String a, char b) {
  return a == null ? -1 : a.lastIndexOf(b);
}


static ThreadLocal<Boolean> DynamicObject_loading = new ThreadLocal();

static class DynamicObject {
  String className; // just the name, without the "main$"
  LinkedHashMap<String,Object> fieldValues = new LinkedHashMap();
  
  DynamicObject() {}
  // className = just the name, without the "main$"
  DynamicObject(String className) {
  this.className = className;}
}/*
 * #!
 * Ontopia Engine
 * #-
 * Copyright (C) 2001 - 2013 The Ontopia Project
 * #-
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * !#
 */

static class CompactHashMap<K, V> extends AbstractMap<K, V> {
  final static int INITIAL_SIZE = 3;
  final static double LOAD_FACTOR = 0.6;

  // This object is used to represent null, should clients use that as
  final static Object nullObject = new Object();
  
  /**
   * When a key is deleted this object is put into the hashtable in
   * its place, so that other entries with the same key (collisions)
   * further down the hashtable are not lost after we delete an object
   * in the collision chain.
   */
  final static Object deletedObject = new Object();
  int elements;
  int freecells;
  K[] keys;
  V[] values; // object at pos x corresponds to key at pos x
  int modCount;

  CompactHashMap() {
    this(INITIAL_SIZE);
  }

  CompactHashMap(int size) {
    keys = (K[]) new Object[(size==0 ? 1 : size)];
    values = (V[]) new Object[(size==0 ? 1 : size)];
    elements = 0;
    freecells = keys.length;
    modCount = 0;
  }

  // ===== MAP IMPLEMENTATION =============================================

  /**
   * Returns the number of key/value mappings in this map.
   */
  public synchronized int size() {
    return elements;
  }
  
  /**
   * Returns <tt>true</tt> if this map contains no mappings.
   */
  public synchronized boolean isEmpty() {
    return elements == 0;
  }

  /**
   * Removes all key/value mappings in the map.
   */
  public synchronized void clear() {
    elements = 0;
    for (int ix = 0; ix < keys.length; ix++) {
      keys[ix] = null;
      values[ix] = null;
    }
    freecells = values.length;
    modCount++;
  }
  
  /**
   * Returns <tt>true</tt> if this map contains the specified key.
   */
  public synchronized boolean containsKey(Object k) {
    return keys[findKeyIndex(k)] != null;
  }
  
  /**
   * Returns <tt>true</tt> if this map contains the specified value.
   */
  public synchronized boolean containsValue(Object v) {
    if (v == null)
      v = (V)nullObject;

    for (int ix = 0; ix < values.length; ix++)
      if (values[ix] != null && values[ix].equals(v))
        return true;

    return false;
  }

  /**
   * Returns a read-only set view of the map's keys.
   */
  public synchronized Set<Entry<K, V>> entrySet() {
    throw new UnsupportedOperationException();
  }

  /**
   * Removes the mapping with key k, if there is one, and returns its
   * value, if there is one, and null if there is none.
   */
  public synchronized V remove(Object k) {
    int index = findKeyIndex(k);

    // we found the right position, now do the removal
    if (keys[index] != null) {
      // we found the object

      // same problem here as with put
      V v = values[index];
      keys[index] = (K) deletedObject;
      values[index] = (V) deletedObject;
      modCount++;
      elements--;
      return v;
    } else
      // we did not find the key
      return null;
  }

  /**
   * Adds the specified mapping to this map, returning the old value for
   * the mapping, if there was one.
   */
  public synchronized V put(K k, V v) {
    if (k == null)
      k = (K)nullObject;

    int hash = k.hashCode();
    int index = (hash & 0x7FFFFFFF) % keys.length;
    int offset = 1;
    int deletedix = -1;
    
    // search for the key (continue while !null and !this key)
    while(keys[index] != null &&
          !(keys[index].hashCode() == hash &&
            keys[index].equals(k))) {

      // if there's a deleted mapping here we can put this mapping here,
      // provided it's not in here somewhere else already
      if (keys[index] == deletedObject)
        deletedix = index;
      
      index = ((index + offset) & 0x7FFFFFFF) % keys.length;
      offset = offset*2 + 1;

      if (offset == -1)
        offset = 2;
    }
    
    if (keys[index] == null) { // wasn't present already
      if (deletedix != -1) // reusing a deleted cell
        index = deletedix;
      else
        freecells--;

      modCount++;
      elements++;

      keys[index] = (K) k;
      values[index] = (V) v;
      
      // rehash with increased capacity
      if (1 - (freecells / (double) keys.length) > LOAD_FACTOR)
        rehash(keys.length*2 + 1);
      return null;
    } else { // was there already
      modCount++;
      V oldv = values[index];
      values[index] = (V) v;
      return oldv;
    }
  }

  /**
   * INTERNAL: Rehashes the hashmap to a bigger size.
   */
  void rehash(int newCapacity) {
    int oldCapacity = keys.length;
    K[] newKeys = (K[]) new Object[newCapacity];
    V[] newValues = (V[]) new Object[newCapacity];

    for (int ix = 0; ix < oldCapacity; ix++) {
      Object k = keys[ix];
      if (k == null || k == deletedObject)
        continue;
      
      int hash = k.hashCode();
      int index = (hash & 0x7FFFFFFF) % newCapacity;
      int offset = 1;

      // search for the key
      while(newKeys[index] != null) { // no need to test for duplicates
        index = ((index + offset) & 0x7FFFFFFF) % newCapacity;
        offset = offset*2 + 1;

        if (offset == -1)
          offset = 2;
      }

      newKeys[index] = (K) k;
      newValues[index] = values[ix];
    }

    keys = newKeys;
    values = newValues;
    freecells = keys.length - elements;
  }

  /**
   * Returns the value for the key k, if there is one, and null if
   * there is none.
   */
  public synchronized V get(Object k) {
    return values[findKeyIndex(k)];
  }

  /**
   * Returns a virtual read-only collection containing all the values
   * in the map.
   */
  public synchronized Collection<V> values() {
    return new ValueCollection();
  }

  /**
   * Returns a virtual read-only set of all the keys in the map.
   */
  public synchronized Set<K> keySet() {
    return new KeySet();
  }

  // --- Internal utilities

  final int findKeyIndex(Object k) {
    if (k == null)
      k = nullObject;

    int hash = k.hashCode();
    int index = (hash & 0x7FFFFFFF) % keys.length;
    int offset = 1;

    // search for the key (continue while !null and !this key)
    while(keys[index] != null &&
          !(keys[index].hashCode() == hash &&
            keys[index].equals(k))) {
      index = ((index + offset) & 0x7FFFFFFF) % keys.length;
      offset = offset*2 + 1;

      if (offset == -1)
        offset = 2;
    }
    return index;
  }
  
  // --- Key set

  class KeySet<K> extends AbstractSet<K> {
    public synchronized int size() {
      return elements;
    }

    public synchronized boolean contains(Object k) {
      return containsKey(k);
    }

    public synchronized Iterator<K> iterator() {
      return new KeyIterator();
    }
  }

  class KeyIterator<K> implements Iterator<K> {
    private int ix;
    
    private KeyIterator() {
      // walk up to first value, so that hasNext() and next() return
      // correct results
      for (; ix < keys.length; ix++)
        if (values[ix] != null && keys[ix] != deletedObject)
          break;
    }

    public synchronized boolean hasNext() {
      return ix < keys.length;
    }

    public synchronized void remove() {
      throw new UnsupportedOperationException("Collection is read-only");
    }

    public synchronized K next() {
      if (ix >= keys.length)
        throw new NoSuchElementException();
      K key = (K) keys[ix++];
      
      // walk up to next value
      for (; ix < keys.length; ix++)
        if (keys[ix] != null && keys[ix] != deletedObject)
          break;
      
      // ix now either points to next key, or outside array (if no next)
      return key;
    }
  }
  
  // --- Value collection

  class ValueCollection<V> extends AbstractCollection<V> {
    public synchronized int size() {
      return elements;
    }

    public synchronized Iterator<V> iterator() {
      return new ValueIterator();
    }

    public synchronized boolean contains(Object v) {
      return containsValue(v);
    }
  }

  class ValueIterator<V> implements Iterator<V> {
    private int ix;
    
    private ValueIterator() {
      // walk up to first value, so that hasNext() and next() return
      // correct results
      for (; ix < values.length; ix++)
        if (values[ix] != null && values[ix] != deletedObject)
          break;
    }

    public synchronized boolean hasNext() {
      return ix < values.length;
    }

    public synchronized void remove() {
      throw new UnsupportedOperationException("Collection is read-only");
    }

    public synchronized V next() {
      if (ix >= values.length)
        throw new NoSuchElementException();
      V value = (V) values[ix++];
      
      // walk up to next value
      for (; ix < values.length; ix++)
        if (values[ix] != null && values[ix] != deletedObject)
          break;
      
      // ix now either points to next value, or outside array (if no next)
      return value;
    }
  }
}static abstract class F1<A, B> {
  abstract B get(A a);
}

static <A, B> void put(Map<A, B> map, A a, B b) {
  if (map != null) map.put(a, b);
}
static <A> Iterator<A> iterator(Collection<A> c) {
  return c == null ? emptyIterator() : c.iterator();
}
// get purpose 1: access a list/array/map (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;
}

// seems to conflict with other signatures
/*static <A, B> B get(Map<A, B> map, A key) {
  ret map != null ? map.get(key) : 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);
    }
      
    
      if (o instanceof DynamicObject)
        return ((DynamicObject) o).fieldValues.get(field);
    
  } 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() & java.lang.reflect.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 <A> void remove(List<A> l, int i) {
  if (l != null && i >= 0 && i < l(l))
    l.remove(i);
}

static <A> void remove(Collection<A> l, A a) {
  if (l != null) l.remove(a);
}


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;
}

}