#include <bits/stdc++.h>
using namespace std;

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int a, b;
  cin >> a >> b;
  long long res = 1;
  for (int k = 0; k < 31; ++k) {
    int x = a >> k & 1;
    int y = b >> k & 1;
    if (x == 1 and y == 0) {
      res *= 0;
    } else if (x == 0 and y == 1) {
      res *= 2;
    }
  }
  res += a == b;
  res /= 2;
  cout << res << '\n';
}