#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 100500;
int main() {
  long long s, x;
  cin >> s >> x;
  if (s < x || (s - x) % 2) {
    cout << 0 << endl;
    return 0;
  }
  if (x == 0) {
    cout << 1 << endl;
    return 0;
  }
  bool eq = s == x;
  long long d = (s - x) / 2;
  long long r = 1;
  while (x || d) {
    if (d & 1) {
      if (x & 1) {
        r = 0;
        break;
      }
    } else if (x & 1) {
      r *= 2;
    } else {
    }
    d /= 2;
    x /= 2;
  }
  if (eq) r -= 2;
  cout << r << 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;
const int inf = 1e9 + 100500;
int main() {
  long long s, x;
  cin >> s >> x;
  if (s < x || (s - x) % 2) {
    cout << 0 << endl;
    return 0;
  }
  if (x == 0) {
    cout << 1 << endl;
    return 0;
  }
  bool eq = s == x;
  long long d = (s - x) / 2;
  long long r = 1;
  while (x || d) {
    if (d & 1) {
      if (x & 1) {
        r = 0;
        break;
      }
    } else if (x & 1) {
      r *= 2;
    } else {
    }
    d /= 2;
    x /= 2;
  }
  if (eq) r -= 2;
  cout << r << endl;
  return 0;
}

```