#include <bits/stdc++.h>
using namespace std;
long long s, x, ans = 1;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> s >> x;
  if ((s - x) % 2) return cout << 0 << endl, 0;
  ;
  s = (s - x) / 2;
  int cnt = 0;
  for (int i = 0; i < 41; i++) {
    int one = (s >> i) & 1, two = (x >> i) & 1;
    if (one == 1 && two == 1) return cout << 0 << endl, 0;
    ;
    if (one == 0 && two == 1)
      ans *= 2;
    else if (one || two)
      cnt++;
  }
  cout << ans - (!cnt) * 2 << endl;
  return 0;
}
