#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
signed main() { 
  ios::sync_with_stdio(false); cin.tie(0);
  long long a, b;
  cin >> a >> b;
  int cnt = 0;
  for (int i = 0; i < 33; i++) {
    // cerr << ((a >> i) & 1) << " " << ((b >> i) & 1) << endl;
    if ((a & (1LL << i)) == 0 && (b & (1LL << i))) cnt++;
    if (((a >> i) & 1) == 1 && (b & (1LL << i)) == 0) {
      cout << 0 << '\n';
      return 0;
    }
  }
  cout << (long long) pow(2, cnt) / 2 << '\n';
  return 0;
}