#include <bits/stdc++.h>
using namespace std;
int main() {
  int flag = 0;
  long long ans = 1, a, b, temp;
  scanf("%I64d%I64d", &a, &b);
  temp = a - b;
  if (temp & 1 || temp < 0) {
    printf("0\n");
    return 0;
  } else {
    temp = temp >> 1;
    if (temp == 0) {
      flag = 1;
    }
    while (b > 0) {
      if (b & 1) {
        ans *= 2;
        if (temp & 1) {
          printf("0\n");
          return 0;
        }
      }
      temp = temp >> 1;
      b = b >> 1;
    }
    if (flag) {
      ans -= 2;
    }
    printf("%I64d\n", 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() {
  int flag = 0;
  long long ans = 1, a, b, temp;
  scanf("%I64d%I64d", &a, &b);
  temp = a - b;
  if (temp & 1 || temp < 0) {
    printf("0\n");
    return 0;
  } else {
    temp = temp >> 1;
    if (temp == 0) {
      flag = 1;
    }
    while (b > 0) {
      if (b & 1) {
        ans *= 2;
        if (temp & 1) {
          printf("0\n");
          return 0;
        }
      }
      temp = temp >> 1;
      b = b >> 1;
    }
    if (flag) {
      ans -= 2;
    }
    printf("%I64d\n", ans);
    return 0;
  }
}

```