#include <bits/stdc++.h>
using namespace std;
int main() {
  long long sum, xors;
  scanf("%lld %lld", &sum, &xors);
  if ((sum - xors) % 2 == 1) {
    printf("0\n");
    return 0;
  }
  if (sum < xors) {
    printf("0\n");
    return 0;
  }
  if (((sum - xors) >> 1) & xors) {
    printf("0\n");
    return 0;
  }
  printf("%lld\n", (1ll << __builtin_popcountll(~((sum - xors) >> 1) & xors)) -
                       (sum == xors ? 2 : 0));
  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;
int main() {
  long long sum, xors;
  scanf("%lld %lld", &sum, &xors);
  if ((sum - xors) % 2 == 1) {
    printf("0\n");
    return 0;
  }
  if (sum < xors) {
    printf("0\n");
    return 0;
  }
  if (((sum - xors) >> 1) & xors) {
    printf("0\n");
    return 0;
  }
  printf("%lld\n", (1ll << __builtin_popcountll(~((sum - xors) >> 1) & xors)) -
                       (sum == xors ? 2 : 0));
  return 0;
}

```