#include <iostream>
using namespace std;
int main() {
    int A, B; cin >> A >> B;
    long long ans = 1;
    for (int i = 0; i <= 30; i++) {
        int a = (A >> i) & 1, b = (B >> i) & 1;
        if (a > b) ans = 0;
        else if (a == 0 && b == 1) ans *= 2;
    }
    cout << (ans == 1 ? 1 : ans/2) << endl;
}