#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
void solve(int test) {
  long long S, X;
  cin >> S >> X;
  if ((S - X) % 2 || S < X) {
    cout << 0 << "\n";
    return;
  }
  long long A = (S - X) / 2;
  long long ans = 1;
  for (int i = 60; i >= 0; i--) {
    int x = (A >> i) & 1;
    int y = (X >> i) & 1;
    if (x == 0 && y == 1)
      ans *= 2;
    else if (x == 1 && y == 1)
      ans = 0;
  }
  if (A == 0) ans -= 2;
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  for (int test = 1; test <= t; test++) {
    solve(test);
  }
  return 0;
}
