#include <bits/stdc++.h>
using namespace std;
 
long long Count(long long s, long long x) {
    long long diff = s - x;
    if (diff < 0 || diff % 2) return 0;
    long long c = diff / 2;
    if ((c & x) != 0) return 0;
    int cnt = __builtin_popcountll(x);
    long long total = 1LL << cnt;
    if (c == 0 && x > 0) total -= 2; 
    return total;
}
 
int main() {
    freopen("sumxor.inp", "r", stdin);
    freopen("sumxor.out", "w", stdout);
    long long s, x;
    cin >> s >> x;
    cout << Count(s, x) << "\n";
}

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