#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main() {
    ll a, b;
    cin >> a >> b;
    int cnt01 = 0;
    for (int i = 0; i < 31; i++) {
        if ((a & (1ll << i)) && !(b & (1ll << i))) {
            cout << 0 << endl;
            return 0;
        }
        else if (!(a & (1ll << i)) && (b & (1ll << i))) cnt01++;
    }
    cout << (1ll << max(0, (cnt01 - 1))) << endl;
}