#include <bits/stdc++.h>
long long s, x, t, g, Res;
int main() {
  int i;
  std::cin >> s >> x;
  if ((s - x) % 2 != 0 || s < x) {
    std::cout << 0;
    return 0;
  }
  t = (s - x) / 2;
  if (t & x) {
    std::cout << 0;
    return 0;
  }
  Res = 1;
  while (x) {
    if (x % 2) Res *= 2;
    x /= 2;
  }
  if (!t) Res -= 2;
  std::cout << Res;
}

### Prompt

In Cpp, your task is to solve 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>
long long s, x, t, g, Res;
int main() {
  int i;
  std::cin >> s >> x;
  if ((s - x) % 2 != 0 || s < x) {
    std::cout << 0;
    return 0;
  }
  t = (s - x) / 2;
  if (t & x) {
    std::cout << 0;
    return 0;
  }
  Res = 1;
  while (x) {
    if (x % 2) Res *= 2;
    x /= 2;
  }
  if (!t) Res -= 2;
  std::cout << Res;
}

```