// See #593 for an example!

import java.util.*;

import java.io.*;

import java.util.regex.*;

import java.net.*;

public class main {

  // My standard packages :)

  static String[] standardClasses = {

    "java.util.*",

    "java.util.regex.*",

    "javax.swing.*",

    "java.io.*",

    "java.net.*"

  };

  public static void main(String[] args) throws IOException {

    String s = loadMainJava();

    List<String> imports = findImports(s);

    for (String c : standardClasses)

      if (!(imports.contains(c)))

        s = "import " + c + ";\n" + s;

    saveMainJava(s);

  }

  static List<String> findImports(String src) {

    List<String> imports = new ArrayList<String>();

    for (String line : toLines(src)) {

      Matcher matcher = Pattern.compile("^\\s*import\\s+(.*?)\\s*;").matcher(line);

      if (matcher.find())

        imports.add(matcher.group(1));

    }

    return imports;

  }

 public static List<String> toLines(String s) {

    List<String> lines = new ArrayList<String>();

    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 loadMainJava() throws IOException {

    return loadTextFile("input/main.java", "");

  }

  static void saveMainJava(String s) throws IOException {

    saveTextFile("output/main.java", s);

  }

  static String charsetForTextFiles = "UTF-8";

  public static String loadTextFile(String fileName, String defaultContents) throws IOException {

    if (!new File(fileName).exists())

      return defaultContents;

    FileInputStream fileInputStream = new FileInputStream(fileName);

    InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, charsetForTextFiles);

    return loadTextFile(inputStreamReader);

  }

  public static String loadTextFile(Reader reader) throws IOException {

    StringBuilder builder = new StringBuilder();

    try {

      BufferedReader bufferedReader = new BufferedReader(reader);

      String line;

      while ((line = bufferedReader.readLine()) != null)

        builder.append(line).append('\n');

    } finally {

      reader.close();

    }

    return builder.length() == 0 ? "" : builder.substring(0, builder.length()-1);

  }

  /** writes safely (to temp file, then rename) */

  public static void saveTextFile(String fileName, String contents) throws IOException {

    File file = new File(fileName);

    File parentFile = file.getParentFile();

    if (parentFile != null)

      parentFile.mkdirs();

    String tempFileName = fileName + "_temp";

    FileOutputStream fileOutputStream = new FileOutputStream(tempFileName);

    OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream, charsetForTextFiles);

    PrintWriter printWriter = new PrintWriter(outputStreamWriter);

    printWriter.print(contents);

    printWriter.close();

    if (file.exists() && !file.delete())

      throw new IOException("Can't delete " + fileName);

    if (!new File(tempFileName).renameTo(file))

      throw new IOException("Can't rename " + tempFileName + " to " + fileName);

  }  

}