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

int main() {
    long a, b, x, d = 0;
    cin >> a >> b;
    x = a ^ b;
    if (a & b != a) {
        cout << 0 << endl;
        return 0;
    }
    while (x) {
        d += x % 2;
        x /= 2;
    }
    cout << ((1l << d) + 1) / 2 << endl;
}