#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define Pr pair<ll,ll>
#define Tp tuple<ll,ll,ll>
using Graph = vector<vector<Pr>>;

ll mod = 998244353;

int main() {
    ll a,b; cin >> a >> b;
    cout << (a^b) << endl;
}