#include <iostream>
#include <algorithm>
#include <queue>
#include <vector>
#include <map>
#include <string>

using namespace std;

void solve();

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
}

void solve() {
    long long int a,c;
    cin >> a >> c;
    cout << (a ^ c) << endl;
}