#include "bits/stdc++.h"

using namespace std;
using ll = long long;

void Main() {
    int A, B;
    cin >> A >> B;
    cout << (A | B) - (A & B) << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    std::cout << std::fixed << std::setprecision(15);
    Main();
    return 0;
}