public static void rmDupChar(BufferedInputStream in)
   {
	   if(in.markSupported()){
	   in.mark(256);
		try {
			count = in.read(b);
			String str = new String(b, 0, count);
			c = str.toCharArray();

		} catch (IOException e) {
			e.printStackTrace();
		}
	   }
	   a.add(c[0]);
    for(i = 1; i < count; i++){
	   temp = c[i];
	   for(j = 0; j < i-1; j++){
		   if (c[j]==temp)
			   break;
	   }
		   if(j == i-1)
			   a.add(temp);
	 }
   }