#include <bits/stdc++.h>
int main() {
  long long a, b, c;
  scanf("%I64d%I64d", &a, &b);
  c = a - b;
  return 0 * printf("%I64d", c >= 0 && (c & (~b << 1)) == c
                                 ? (1ll << __builtin_popcountll(b)) - 2 * (!c)
                                 : 0);
}

### Prompt

Create a solution in Cpp for 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>
int main() {
  long long a, b, c;
  scanf("%I64d%I64d", &a, &b);
  c = a - b;
  return 0 * printf("%I64d", c >= 0 && (c & (~b << 1)) == c
                                 ? (1ll << __builtin_popcountll(b)) - 2 * (!c)
                                 : 0);
}

```