#include <bits/stdc++.h>
using namespace std;
void fs(long long &num) {
  num = 0;
  register int c;
  bool sign = false;
  c = getchar();
  if (c == '-') {
    sign = true;
    c = getchar();
  }
  for (; c > 47 && c < 58; c = getchar()) {
    num *= 10;
    num += c - 48;
  }
  if (sign) num *= -1;
}
bool a[140];
int main() {
  long long s, x, co_x, ans = 1;
  fs(s), fs(x);
  if (s < x) {
    cout << "0\n";
    return 0;
  }
  co_x = x;
  vector<int> q;
  while (co_x > 0) {
    q.push_back(co_x % 2);
    co_x /= 2;
  }
  for (int i = 0; i < q.size(); ++i) {
    if (q[i] == 1) {
      ans *= 2;
      a[i] = 1;
    }
  }
  s -= x;
  if (s == 0) {
    ans -= 2;
    cout << ans << '\n';
    return 0;
  }
  q.clear();
  while (s > 0) {
    q.push_back(s % 2);
    s /= 2;
  }
  if (q[0] == 1) {
    cout << "0\n";
    return 0;
  }
  for (int i = 1; i < q.size(); ++i) {
    if (q[i] == 1 && a[i - 1] == 1) ans = 0;
  }
  cout << ans << '\n';
}
