#include "bits/stdc++.h"
#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 1000000007;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int A, B; cin >> A >> B;
	cout << (A | B) - (A&B) << endl;
	return 0;

}