#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int s, x, y, a, b = 0;
  cin >> s >> x;
  int f = 1;
  if (s < x) f = 0;
  if (s == x) b = 2;
  y = s - x;
  if (y % 2 == 1) f = 0;
  if (f) {
    y /= 2, a = 1;
    while (x > 0 || y > 0) {
      if (x % 2 == 1) {
        if (y % 2 == 0)
          a *= 2;
        else
          f = 0;
      }
      x /= 2, y /= 2;
    }
  }
  a *= f;
  cout << a - b << endl;
}

### 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 int s, x, y, a, b = 0;
  cin >> s >> x;
  int f = 1;
  if (s < x) f = 0;
  if (s == x) b = 2;
  y = s - x;
  if (y % 2 == 1) f = 0;
  if (f) {
    y /= 2, a = 1;
    while (x > 0 || y > 0) {
      if (x % 2 == 1) {
        if (y % 2 == 0)
          a *= 2;
        else
          f = 0;
      }
      x /= 2, y /= 2;
    }
  }
  a *= f;
  cout << a - b << endl;
}

```