#include <bits/stdc++.h>
using namespace std;
long long s, x;
int main() {
  cin >> s >> x;
  s -= x;
  if (s < 0 || s % 2 != 0) {
    cout << 0 << endl;
    return 0;
  }
  s /= 2;
  if (s & x) {
    cout << 0 << endl;
    return 0;
  }
  long long bit = 0, result = 0;
  if (!s) result -= 2;
  while (x > 0) {
    bit += x & 1;
    x >>= 1;
  }
  result += 1LL << bit;
  cout << result << 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;
  s -= x;
  if (s < 0 || s % 2 != 0) {
    cout << 0 << endl;
    return 0;
  }
  s /= 2;
  if (s & x) {
    cout << 0 << endl;
    return 0;
  }
  long long bit = 0, result = 0;
  if (!s) result -= 2;
  while (x > 0) {
    bit += x & 1;
    x >>= 1;
  }
  result += 1LL << bit;
  cout << result << endl;
  return 0;
}

```