#include <bits/stdc++.h>
using namespace std;
const int maxN = 200009;
vector<int> a;
vector<int> b;
vector<int> bb;
int main() {
  long long s, x;
  cin >> s >> x;
  int s1 = s, x1 = x;
  int ans = 0;
  for (int i = 0; i < 45; i++) {
    if ((s & ((long long)1 << i)) && (x & ((long long)1 << i))) ans++;
    if (!(s & ((long long)1 << i)) && (x & ((long long)1 << i))) {
      cout << 0;
      return 0;
    }
    if ((s & ((long long)1 << i)) && !(x & ((long long)1 << i))) {
      cout << 0;
      return 0;
    }
    if (!(s & ((long long)1 << i)) && !(x & ((long long)1 << i))) {
      if ((s & ((long long)1 << (i + 1))) && !(x & ((long long)1 << (i + 1)))) {
        s -= ((long long)1 << (i + 1));
      }
      if (!(s & ((long long)1 << (i + 1))) && (x & ((long long)1 << (i + 1)))) {
        s -= ((long long)1 << (i + 1));
      }
    }
  }
  if (s1 != x1)
    cout << ((long long)1 << ans);
  else
    cout << ((long long)1 << ans) - 2;
  return 0;
}
