#include <bits/stdc++.h>
using namespace std;
template <class T>
bool umin(T& a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool umax(T& a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
int main() {
  long long s, x;
  scanf("%lld%lld", &s, &x);
  long long a = (s - x) / 2;
  if (a < 0 or x + 2 * a != s or (x & a) != 0) return puts("0") * 0;
  long long tmp = x, res = 0;
  while (tmp > 0) {
    res += tmp & 1;
    tmp /= 2;
  }
  long long ans = (1LL << res);
  if (!a) ans -= 2;
  printf("%lld\n", ans);
  return 0;
}
