#include <bits/stdc++.h>
using namespace std;
long long S, X;
int main() {
  cin >> S >> X;
  int d = 0;
  if (S == X) d = -2;
  long long ans = 1;
  for (int c = 0; c < 60; c++) {
    if ((S & 1) != (X & 1)) {
      cout << 0 << endl;
      return 0;
    } else if ((X & 1) == 1) {
      ans *= 2;
      X >>= 1;
      S >>= 1;
    } else {
      if ((X & 2) != (S & 2)) {
        X >>= 1;
        S >>= 1;
        S--;
      } else {
        X >>= 1;
        S >>= 1;
      }
    }
  }
  cout << ans + d << 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;
long long S, X;
int main() {
  cin >> S >> X;
  int d = 0;
  if (S == X) d = -2;
  long long ans = 1;
  for (int c = 0; c < 60; c++) {
    if ((S & 1) != (X & 1)) {
      cout << 0 << endl;
      return 0;
    } else if ((X & 1) == 1) {
      ans *= 2;
      X >>= 1;
      S >>= 1;
    } else {
      if ((X & 2) != (S & 2)) {
        X >>= 1;
        S >>= 1;
        S--;
      } else {
        X >>= 1;
        S >>= 1;
      }
    }
  }
  cout << ans + d << endl;
  return 0;
}

```