#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
using ll = long long;
const int INF = (int)1e9 + 7, mod = (int)1e9 + 9, pw = 31, N = (int)1e5 + 123,
          M = (int)1e6 + 123;
const double eps = 1e-11;
const long long inf = 1e18;
ll n, m, ans = 0;
bitset<60> a, b, d;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cin >> n >> m;
  ll res = 0;
  a = n;
  b = m;
  if ((n - m) % 2 != 0 || n % 2 != m % 2) {
    cout << "0";
    return 0;
  }
  d = (n - m) / 2;
  if ((d & b).count()) {
    cout << "0";
    return 0;
  }
  cout << (1ll << (b.count())) - (n == m ? 2 : 0);
  return 0;
}
