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

int main() {
  int a, b;
  cin >> a >> b;
  int ans = (a | b) - (a & b);
  cout << ans << endl;
  return 0;
}