#include <bits/stdc++.h>
using namespace std;
long long a, b;
long long count(long long a) {
  int c = 0;
  for (int i = 0; i < 50; ++i)
    if (a >> i & 1) ++c;
  return c;
}
int main() {
  cin >> a >> b;
  if (a == b)
    cout << (1LL << count(a)) - 2 << endl;
  else {
    long long d = a - b;
    if ((d & 1) || (b & (d >> 1)))
      cout << 0 << endl;
    else
      cout << (1LL << count(b)) << 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;
long long a, b;
long long count(long long a) {
  int c = 0;
  for (int i = 0; i < 50; ++i)
    if (a >> i & 1) ++c;
  return c;
}
int main() {
  cin >> a >> b;
  if (a == b)
    cout << (1LL << count(a)) - 2 << endl;
  else {
    long long d = a - b;
    if ((d & 1) || (b & (d >> 1)))
      cout << 0 << endl;
    else
      cout << (1LL << count(b)) << endl;
  }
  return 0;
}

```