#include <bits/stdc++.h>
using namespace std;
long long s, x;
int main() {
  cin >> s >> x;
  long long t = s;
  long long cnt = 1;
  for (int i = 0; i < 64; i++) {
    if (x & ((long long)1 << i)) {
      cnt *= 2;
      s -= ((long long)1 << i);
    }
  }
  if (s % 2) {
    cout << 0 << endl;
    return 0;
  }
  s /= 2;
  if (s < 0)
    cout << 0 << endl;
  else {
    for (int i = 0; i < 64; i++) {
      if (s & ((long long)1 << i) && x & ((long long)1 << i)) {
        cout << 0 << endl;
        return 0;
      }
    }
    if (t == x) cnt -= 2;
    cout << cnt << endl;
  }
}
