#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long s, x;
  cin >> s >> x;
  if ((s - x) % 2 == 1) {
    cout << 0;
    return 0;
  }
  long long a = (s - x) / 2;
  long long flag = 0;
  long long y = 0;
  long long s1 = s;
  long long x1 = x;
  while (x > 0) {
    long long q = x & 1;
    long long r = a & 1;
    if (q == 1) {
      if (r == 0)
        y++;
      else
        flag = 1;
    }
    a = a >> 1;
    x = x >> 1;
  }
  if (flag == 1)
    cout << 0;
  else {
    if (s1 == x1)
      cout << (long long)pow(2, y) - 2;
    else
      cout << (long long)pow(2, y);
  }
}
