Hack

import java.io.*;public class RegEx{	public static void main(String[] args) throws Exception	{    BufferedReader f = new BufferedReader(new FileReader("x.txt"));    String str = f.readLine();		String[] hexs = str.split("%");		for(int i = 1;i < hexs.length; i++)		{			int c = (((dec(hexs[i].charAt(0))) * 16) + (dec(hexs[i].charAt(1))));			char ch = (char)c;			System.out.print(ch);		}	}	public static int dec(char ch)	{		if(Character.isDigit(ch))			return ch - '0';		return ch-'a'+10;	}}