#include <bits/stdc++.h>
using namespace std;
int main() {
  long long S, X;
  cin >> S >> X;
  long long A = S - X;
  if (A < 0 or A % 2 == 1) {
    cout << 0 << endl;
    return 0;
  }
  long long B = A / 2;
  long long solution = 1;
  long long temp = 1;
  for (int i = 0; i <= 40; i++) {
    if (X & (temp << i)) {
      if (B & (temp << i)) {
        cout << 0 << endl;
        return 0;
      }
      solution *= 2;
    }
  }
  if (A == 0) solution -= 2;
  cout << solution << endl;
  return 0;
}

### Prompt

Please create a solution in Cpp 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() {
  long long S, X;
  cin >> S >> X;
  long long A = S - X;
  if (A < 0 or A % 2 == 1) {
    cout << 0 << endl;
    return 0;
  }
  long long B = A / 2;
  long long solution = 1;
  long long temp = 1;
  for (int i = 0; i <= 40; i++) {
    if (X & (temp << i)) {
      if (B & (temp << i)) {
        cout << 0 << endl;
        return 0;
      }
      solution *= 2;
    }
  }
  if (A == 0) solution -= 2;
  cout << solution << endl;
  return 0;
}

```