#include <bits/stdc++.h>
using namespace std;
long long int po(long long int c) {
  long long int an = 1;
  for (int i = 0; i < c; i++) an *= 2;
  return an;
}
int main() {
  bool f[50];
  bool fs[50];
  for (int i = 0; i < 50; i++) {
    f[i] = false;
    fs[i] = false;
  }
  long long int s, x, t = 0;
  cin >> s >> x;
  long long int n = x, c = 0;
  while (n > 0) {
    if (n % 2 == 1) {
      f[c] = 1;
      t++;
    }
    c++;
    n /= 2;
  }
  s -= x;
  if (s < 0) {
    cout << "0";
    return 0;
  }
  if (s == 0) {
    cout << po(t) - 2;
    return 0;
  }
  if (s % 2 != 0) {
    cout << "0";
    return 0;
  }
  n = s / 2, c = 0;
  while (n > 0) {
    if (n % 2 == 1) {
      fs[c] = 1;
    }
    c++;
    n /= 2;
  }
  s /= 2;
  c = 49;
  for (int i = 0; i < 50; i++)
    if (fs[i] && f[i]) {
      cout << "0";
      return 0;
    }
  cout << po(t);
  return 0;
}
