/******************************************************************************
 * Program computes a simple checksum of STDIN
 * 
 * Copyright © 2017 Richard Lesh.  All rights reserved.
 *****************************************************************************/

import org.pureprogrammer.Utils;

public class SimpleChecksum2 {

    public static void main(String[] args) {
        int c;
        int temp = 0;
        long count = 0;
        int checksum = 0;
        while ((c = Utils.getbyte(System.in)) != -1) {
            temp = c;
            temp <<= (3 - (count % 4)) * 8;
            checksum ^= temp;
            ++count;
        }
        String result = Utils.toHex(checksum);
        System.out.println(Utils.cpSubstring(result, Utils.cpLength(result) - 8));
    }
}