#include <iostream> #include <vector> #include <string> #include <cmath> #include <algorithm> #include <utility> #include <queue> #include <set> #include <map> using namespace std; typedef long long ll; typedef pair<int,int> PII; typedef vector<int> VI; typedef vector<VI> VVI; #define MP make_pair #define PB push_back #define inf 1000000007 long long mod = 1000000007; int main(){ ll a,c; cin >> a >> c; cout << (a^c) << endl; return 0; }