#include <bits/stdc++.h>
using namespace std;
int main() {
  long long i, j, k, l, m, n, ans = 1;
  cin >> n >> m;
  if ((n - m) < 0 || (n - m) % 2 || ((n - m) / 2) & m)
    return cout << 0 << '\n', 0;
  l = m;
  while (l) {
    l = l & (l - 1);
    ans = ans * 2;
  }
  if ((n - m) == 0) ans -= 2;
  cout << ans << '\n';
}

### Prompt

In cpp, your task is to solve 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 i, j, k, l, m, n, ans = 1;
  cin >> n >> m;
  if ((n - m) < 0 || (n - m) % 2 || ((n - m) / 2) & m)
    return cout << 0 << '\n', 0;
  l = m;
  while (l) {
    l = l & (l - 1);
    ans = ans * 2;
  }
  if ((n - m) == 0) ans -= 2;
  cout << ans << '\n';
}

```