#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  long long sum, _xor;
  cin >> sum >> _xor;
  long long _and = (sum - _xor);
  if (_and % 2 == 1) {
    cout << 0 << endl;
    return 0;
  }
  _and /= 2;
  long long res = 1;
  for (int go = 0; go < 60; go++) {
    if (_xor & (1LL << go)) {
      if (_and & (1LL << go)) {
        cout << 0 << endl;
        return 0;
      }
      res <<= 1;
    }
  }
  if (sum == _xor) res -= 2;
  cout << res << endl;
  return 0;
}

### Prompt

Your task is to create a cpp solution to the following problem:

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() {
  ios::sync_with_stdio(false);
  long long sum, _xor;
  cin >> sum >> _xor;
  long long _and = (sum - _xor);
  if (_and % 2 == 1) {
    cout << 0 << endl;
    return 0;
  }
  _and /= 2;
  long long res = 1;
  for (int go = 0; go < 60; go++) {
    if (_xor & (1LL << go)) {
      if (_and & (1LL << go)) {
        cout << 0 << endl;
        return 0;
      }
      res <<= 1;
    }
  }
  if (sum == _xor) res -= 2;
  cout << res << endl;
  return 0;
}

```