#include <bits/stdc++.h>
using namespace std;
long long s, x;
int flag = 0;
int main() {
  cin >> s >> x;
  if (s == x) flag = 1;
  s -= x;
  if (s % 2 == 1) return puts("0");
  s /= 2;
  long long ans = 1;
  for (int i = 0; i < 60; i++) {
    int p1 = (s >> i) & 1;
    int p2 = (x >> i) & 1;
    if (p2 == 1 && p1 == 1) return puts("0");
    if (p2 == 1) ans *= 2;
  }
  if (flag) ans -= 2;
  cout << ans << endl;
}

### Prompt

Please formulate 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;
int flag = 0;
int main() {
  cin >> s >> x;
  if (s == x) flag = 1;
  s -= x;
  if (s % 2 == 1) return puts("0");
  s /= 2;
  long long ans = 1;
  for (int i = 0; i < 60; i++) {
    int p1 = (s >> i) & 1;
    int p2 = (x >> i) & 1;
    if (p2 == 1 && p1 == 1) return puts("0");
    if (p2 == 1) ans *= 2;
  }
  if (flag) ans -= 2;
  cout << ans << endl;
}

```