package codeup100;

import java.util.Scanner;

public class c1062 {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

String[] nums = sc.nextLine().split(" ");

sc.close();

int num1 = Integer.parseInt(nums[0]);

int num2 = Integer.parseInt(nums[1]);

System.out.println(num1^num2);

}

}