#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int i, j, s, x, n, out = 1, temp = 1;
  cin >> s >> x;
  j = (s - x) >> 1;
  if ((s - x) & 1 || s - x < 0 || (j & x) != 0) {
    cout << 0 << endl;
    return 0;
  }
  bitset<64> bx(x);
  for (i = 0; i < 64; i++) {
    if (bx[i] == 1) out *= 2;
  }
  if (s == x) out -= 2;
  cout << out << endl;
}

### Prompt

Please provide a cpp coded solution 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() {
  long long int i, j, s, x, n, out = 1, temp = 1;
  cin >> s >> x;
  j = (s - x) >> 1;
  if ((s - x) & 1 || s - x < 0 || (j & x) != 0) {
    cout << 0 << endl;
    return 0;
  }
  bitset<64> bx(x);
  for (i = 0; i < 64; i++) {
    if (bx[i] == 1) out *= 2;
  }
  if (s == x) out -= 2;
  cout << out << endl;
}

```