UVA Problem ID 272 ( TeX Quotes )

import java.io.*;

public class Main {

    static String ReadLn (int maxLg)  // utility function to read from stdin
    {
        byte lin[] = new byte [maxLg];
        int lg = 0, car = -1;
        String line = "";

        try
        {
            while (lg < maxLg)
            {
                car = System.in.read();
                if ((car < 0) || (car == '\n')) break;
                lin [lg++] += car;
            }
        }
        catch (IOException e)
        {
            return (null);
        }

        if ((car < 0) && (lg == 0)) return (null);  // eof
        return (new String (lin, 0, lg));
    }

    public static void main (String args[])  // entry point from OS
    {
        Main myWork = new Main();  // create a dynamic instance
        myWork.Begin();            // the true entry point
    }

    void Begin()
    {
        String input;
        StringBuilder s;
          boolean starting=true;

        while ((input = Main.ReadLn (255)) != null)
        {
                s=new StringBuilder(input);
          while(s.indexOf("\"")!=-1)
          {
                if(starting)
                {
                        s.replace(s.indexOf("\""),s.indexOf("\"")+1, "``");
                        starting=false;
                }
                else {
                        s.replace(s.indexOf("\""),s.indexOf("\"")+1, "''");
                        starting=true;
}
          }
          System.out.println(s);
        }
    }
}