#include <bits/stdc++.h>
using namespace std;
long long s, x, a, ans = 1;
void setup() {
  cin >> s >> x;
  a = s - x;
  if (a & 1) {
    cout << 0;
    exit(0);
  }
  a >>= 1;
}
void xuly() {
  long long k = a;
  while (x) {
    if (x & 1) {
      if (a & 1) {
        cout << 0;
        return;
      }
      ans <<= 1;
    }
    x >>= 1;
    a >>= 1;
  }
  if (k == 0) ans -= 2;
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  setup();
  xuly();
  return 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>
using namespace std;
long long s, x, a, ans = 1;
void setup() {
  cin >> s >> x;
  a = s - x;
  if (a & 1) {
    cout << 0;
    exit(0);
  }
  a >>= 1;
}
void xuly() {
  long long k = a;
  while (x) {
    if (x & 1) {
      if (a & 1) {
        cout << 0;
        return;
      }
      ans <<= 1;
    }
    x >>= 1;
    a >>= 1;
  }
  if (k == 0) ans -= 2;
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  setup();
  xuly();
  return 0;
}

```