#include <bits/stdc++.h>
using namespace std;
int main() {
  long long ans = 1;
  long long s, x;
  cin >> s >> x;
  long long t = s - x;
  if (t % 2 || t < 0) return 0 * puts("0");
  t >>= 1;
  for (int i = 0; i < 60; i++) {
    long long p = (1LL << i);
    if (p > x || p > s) break;
    if (!(p & t) && (p & x)) ans *= 2;
    if ((p & t) && (p & x)) return 0 * puts("0");
  }
  if (s == x) ans -= 2;
  cout << ans << endl;
  return 0;
}

### Prompt

Please provide a Cpp coded solution to the problem described below:

Two positive integers a and b have a sum of s and a bitwise XOR of x. How many possible values are there for the ordered pair (a, b)?

Input

The first line of the input contains two integers s and x (2 ≤ s ≤ 1012, 0 ≤ x ≤ 1012), the sum and bitwise xor of the pair of positive integers, respectively.

Output

Print a single integer, the number of solutions to the given conditions. If no solutions exist, print 0.

Examples

Input

9 5


Output

4


Input

3 3


Output

2


Input

5 2


Output

0

Note

In the first sample, we have the following solutions: (2, 7), (3, 6), (6, 3), (7, 2).

In the second sample, the only solutions are (1, 2) and (2, 1).

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int main() {
  long long ans = 1;
  long long s, x;
  cin >> s >> x;
  long long t = s - x;
  if (t % 2 || t < 0) return 0 * puts("0");
  t >>= 1;
  for (int i = 0; i < 60; i++) {
    long long p = (1LL << i);
    if (p > x || p > s) break;
    if (!(p & t) && (p & x)) ans *= 2;
    if ((p & t) && (p & x)) return 0 * puts("0");
  }
  if (s == x) ans -= 2;
  cout << ans << endl;
  return 0;
}

```