#include <bits/stdc++.h>
using namespace std;
long long s;
long long x;
long long Solve() {
  long long sol = 1;
  long long ss = s;
  for (int i = 50; i >= 0; i--) {
    if ((x >> i) & 1) {
      s -= (1ll << i);
      sol *= 2;
    } else {
      if ((s >> (i + 1)) & 1) s -= (1ll << (i + 1));
    }
  }
  if (s) return 0;
  if (ss == x) sol -= 2;
  return sol;
}
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> s >> x;
  cout << Solve() << "\n";
  return 0;
}

### Prompt

Generate a Cpp solution 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;
long long s;
long long x;
long long Solve() {
  long long sol = 1;
  long long ss = s;
  for (int i = 50; i >= 0; i--) {
    if ((x >> i) & 1) {
      s -= (1ll << i);
      sol *= 2;
    } else {
      if ((s >> (i + 1)) & 1) s -= (1ll << (i + 1));
    }
  }
  if (s) return 0;
  if (ss == x) sol -= 2;
  return sol;
}
int main() {
  ios_base ::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> s >> x;
  cout << Solve() << "\n";
  return 0;
}

```