#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const double eps = 1e-15;
double PI = 3.14159265359;
const int INF = 1e9;
const int N = 1000001;
;
int n, t;
long long s, x, a, r = 1;
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> s >> x;
  if ((s - x) & 1) {
    cout << 0;
    return 0;
  }
  a = (s - x) >> 1;
  if (a & x) {
    cout << 0;
    return 0;
  }
  for (int i = 0; i < 50; i++)
    if (x & 1LL << i) r <<= 1;
  if (!a) r -= 2;
  cout << r;
}
