#include <bits/stdc++.h>
using namespace std;
int main() {
  std::ios_base::sync_with_stdio(false);
  long long s, first;
  cin >> s >> first;
  if (s < first) {
    cout << 0;
    return 0;
  }
  long long d = s - first;
  int l = 0;
  while (d > 0) {
    if (d & 1ll) {
      if (!(l - 1 >= 0 && ((1ll << (l - 1)) & first) == 0)) {
        cout << 0;
        return 0;
      }
    }
    d >>= 1;
    l++;
  }
  cout << ((1ll << __builtin_popcountll(first)) - (s - first == 0ll) * 2);
  return 0;
}

### Prompt

Create a solution in CPP for 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() {
  std::ios_base::sync_with_stdio(false);
  long long s, first;
  cin >> s >> first;
  if (s < first) {
    cout << 0;
    return 0;
  }
  long long d = s - first;
  int l = 0;
  while (d > 0) {
    if (d & 1ll) {
      if (!(l - 1 >= 0 && ((1ll << (l - 1)) & first) == 0)) {
        cout << 0;
        return 0;
      }
    }
    d >>= 1;
    l++;
  }
  cout << ((1ll << __builtin_popcountll(first)) - (s - first == 0ll) * 2);
  return 0;
}

```