#include <bits/stdc++.h>
using namespace std;
long long a, s, x, ans = 1;
int mian() {}
int main() {
  cin >> s >> x;
  a = s - x;
  if (a < 0 || (a & 1)) {
    puts("0");
    return 0;
  }
  a >>= 1;
  s = a ? 0 : -2;
  while (x) {
    if ((a & 1) && (x & 1)) {
      puts("0");
      return 0;
    }
    if (!(a & 1) && (x & 1)) ans <<= 1;
    x >>= 1;
    a >>= 1;
  }
  cout << ans + s;
}

### Prompt

Please provide a cpp coded solution 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;
long long a, s, x, ans = 1;
int mian() {}
int main() {
  cin >> s >> x;
  a = s - x;
  if (a < 0 || (a & 1)) {
    puts("0");
    return 0;
  }
  a >>= 1;
  s = a ? 0 : -2;
  while (x) {
    if ((a & 1) && (x & 1)) {
      puts("0");
      return 0;
    }
    if (!(a & 1) && (x & 1)) ans <<= 1;
    x >>= 1;
    a >>= 1;
  }
  cout << ans + s;
}

```