#include <bits/stdc++.h>
using namespace std;
long long s, x, y, ans;
int main() {
  scanf("%I64d %I64d", &s, &x);
  if (s < x) {
    puts("0");
    return 0;
  }
  ans = 1;
  y = s - x;
  if (y & 1) {
    puts("0");
    return 0;
  }
  for (int i = (0); i < (60); i++) {
    if (x & 1LL << i) {
      if (y & 1LL << i + 1)
        ans = 0;
      else
        ans *= 2;
    }
  }
  if (s == x) ans -= 2;
  printf("%I64d\n", ans);
  scanf("\n");
}

### Prompt

Your task is to create 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;
long long s, x, y, ans;
int main() {
  scanf("%I64d %I64d", &s, &x);
  if (s < x) {
    puts("0");
    return 0;
  }
  ans = 1;
  y = s - x;
  if (y & 1) {
    puts("0");
    return 0;
  }
  for (int i = (0); i < (60); i++) {
    if (x & 1LL << i) {
      if (y & 1LL << i + 1)
        ans = 0;
      else
        ans *= 2;
    }
  }
  if (s == x) ans -= 2;
  printf("%I64d\n", ans);
  scanf("\n");
}

```