#include <bits/stdc++.h>
using namespace std;
int main() {
  long long s, x;
  cin >> s >> x;
  long long andd = (s - x) >> 1;
  if (s < x || (s - x) % 2 != 0 || (x & andd) != 0) return puts("0"), 0;
  int bit = 0;
  while (x) {
    if (x & 1) ++bit;
    x >>= 1;
  }
  long long ans = 1ll << bit;
  if (andd == 0) ans -= 2;
  cout << ans << endl;
  return 0;
}

### Prompt

Construct a CPP code solution to the problem outlined:

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 s, x;
  cin >> s >> x;
  long long andd = (s - x) >> 1;
  if (s < x || (s - x) % 2 != 0 || (x & andd) != 0) return puts("0"), 0;
  int bit = 0;
  while (x) {
    if (x & 1) ++bit;
    x >>= 1;
  }
  long long ans = 1ll << bit;
  if (andd == 0) ans -= 2;
  cout << ans << endl;
  return 0;
}

```