#include <bits/stdc++.h>
using namespace std;
int main() {
  uint64_t s, x;
  cin >> s >> x;
  if (s < x) {
    cout << 0 << endl;
    return 0;
  }
  uint64_t r = (s - x);
  if (r & 1) {
    cout << 0 << endl;
    return 0;
  }
  r >>= 1;
  uint64_t ans = 1;
  for (int i = 0; i < 64; i++) {
    uint64_t k = 1ull << i;
    if ((r & k) && (x & k)) {
      cout << 0 << endl;
      return 0;
    }
    if (!(r & k) && (x & k)) ans <<= 1;
  }
  ans -= r ? 0 : 2;
  cout << ans << 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() {
  uint64_t s, x;
  cin >> s >> x;
  if (s < x) {
    cout << 0 << endl;
    return 0;
  }
  uint64_t r = (s - x);
  if (r & 1) {
    cout << 0 << endl;
    return 0;
  }
  r >>= 1;
  uint64_t ans = 1;
  for (int i = 0; i < 64; i++) {
    uint64_t k = 1ull << i;
    if ((r & k) && (x & k)) {
      cout << 0 << endl;
      return 0;
    }
    if (!(r & k) && (x & k)) ans <<= 1;
  }
  ans -= r ? 0 : 2;
  cout << ans << endl;
  return 0;
}

```