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

using ll = long long;
const ll MOD = 998244353;

int main() {
    ll A, B;
    cin >> A >> B;
    ll ans = 1;
    rep(i, 30) {
        int c = A % 2, d = B % 2;
        if (c == 1 && d == 0) {
            cout << 0 << endl;
            return 0;
        }
        if (c == 0 && d == 1) ans *= 2;
        A /= 2;
        B /= 2;
    }
    if (ans > 1) ans /= 2;
    cout << ans << endl;
}