#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <cmath>
#include <string>
#include<sstream>
#include <queue>
#include <limits>
#include <cstdlib>
#include <deque>
using namespace std;

int main() {

	int a =0;
	int b =0;

	cin>>a>>b;

	int c = a^b;
	cout<<c;



	return 0;
}