#include <bits/stdc++.h>
using namespace std;
vector<bool> sum, op;
int main() {
  ios_base::sync_with_stdio(false);
  long long s, x, cs, cx;
  cin >> s >> x;
  cs = s;
  cx = x;
  long long ways_c = 0, ways = 1;
  while (x != 0 or s != 0) {
    int bone = s % 2, btwo = x % 2;
    if (bone and btwo) {
      ways = ways * 2;
      ways_c = 0;
    } else if (bone) {
      ways = ways_c;
      ways_c = ways_c;
    } else if (btwo) {
      ways = 0;
      ways_c = ways_c * 2;
    } else {
      ways = ways;
      ways_c = ways;
    }
    x /= 2;
    s /= 2;
  }
  if (cs == cx) ways -= 2;
  cout << ways << endl;
}
