#include <bits/stdc++.h>
using namespace std;
int main() {
  long long s, x;
  cin >> s >> x;
  vector<int> v;
  s -= x;
  if (s % 2 == 1 || s < 0) {
    cout << 0;
    return 0;
  }
  while (x) {
    v.push_back(x % 2);
    x /= 2;
  }
  long long ans = 1;
  for (int i = 0; i < v.size(); i++) {
    if (v[i]) {
      ans *= 2;
    }
  }
  vector<int> vs;
  if (s == 0) {
    ans -= 2;
  } else {
    s /= 2;
    while (s) {
      vs.push_back(s % 2);
      s /= 2;
    }
    for (int i = 0; i < vs.size(); i++) {
      if (i < v.size() && vs[i]) {
        if (v[i]) {
          ans = 0;
          break;
        }
      }
    }
  }
  cout << ans;
  return 0;
}

### Prompt

Develop a solution in Cpp 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;
int main() {
  long long s, x;
  cin >> s >> x;
  vector<int> v;
  s -= x;
  if (s % 2 == 1 || s < 0) {
    cout << 0;
    return 0;
  }
  while (x) {
    v.push_back(x % 2);
    x /= 2;
  }
  long long ans = 1;
  for (int i = 0; i < v.size(); i++) {
    if (v[i]) {
      ans *= 2;
    }
  }
  vector<int> vs;
  if (s == 0) {
    ans -= 2;
  } else {
    s /= 2;
    while (s) {
      vs.push_back(s % 2);
      s /= 2;
    }
    for (int i = 0; i < vs.size(); i++) {
      if (i < v.size() && vs[i]) {
        if (v[i]) {
          ans = 0;
          break;
        }
      }
    }
  }
  cout << ans;
  return 0;
}

```