#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(NULL);
  long long i, j, n, m, s, x;
  cin >> s >> x;
  long long exc = (s - x) / 2;
  if (exc < 0 || (s - x) % 2 != 0) {
    cout << 0;
    return 0;
  }
  long long cnt = 1;
  long long tot = 0;
  if (exc == 0) tot = -2;
  while (x > 0 || exc > 0) {
    long long e1 = x % 2;
    long long e2 = exc % 2;
    if (e1 == 1) {
      if (e2 == 1)
        cnt = 0;
      else
        cnt *= 2;
    }
    x /= 2;
    exc /= 2;
  }
  cnt += tot;
  cout << cnt;
  return 0;
}
