//#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
//using namespace atcoder;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
Graph G;
vll dist;
vector<bool> seen;
vll T;
vector<bool> C;
vector<bool> CHA;
ll mod = 1e9 + 7;



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