#include <bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define ll long long


int main(){
    fast

    int a,b;
    cin >> a >> b;

    cout << (a|b) - (a&b)<<endl;
    
    return 0;
}