#include <bits/stdc++.h>   using namespace std;   int main() {     long long s, x;     cin >> s >> x;     long long ans = __builtin_popcountll(x);     ans = 1LL << ans;     if (s == x) ans -= 2;     for (int i = 0; i < 60; i++) {       if (x & (1LL << i)) s -= 1LL << i;     }     for (int i = 0; i < 60; i++) {       int j = i + 1;       if ((s & (1LL << j)) && !(x & (1LL << i))) s -= 1LL << j;     }     if (s != 0)       puts( 0 );     else       cout << ans << endl;   }   