#include <bits/stdc++.h>
#include <math.h>

using namespace std;

using ll = long long;
using pp = pair<int,int>;
#define rep(i,n) for(int i = 0;i<n;i++)
#define printv(v) for(auto x : v) cout << x << " "; cout << "\n";    // v の要素を表示
#define printv2(v) for(auto x : v) {printv(x);cout << "\n";};



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