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

int main(){
  ll A, B; cin >> A >> B;

  ll ans = 1;
  for(int dgt=0; dgt<32; dgt++){
    ll msk = 1LL<<dgt;
    bool a = A&msk, b = B&msk;
    if(a && !b) ans = 0;
    if(!a && b) ans *= 2;
  }
  ans /= 2;
  cout << ans << endl;
}