#include <bits/stdc++.h>
using namespace std;
int bitcount(long long x) {
  int ret = 0;
  while (x) {
    if (x & 1) ++ret;
    x >>= 1;
  }
  return ret;
}
int main() {
  long long s, x;
  cin >> s >> x;
  if (s < x || (s - x) & 1 || ((((s - x) >> 1) & x) != 0)) {
    printf("0\n");
    return 0;
  }
  s -= x;
  s >>= 1;
  if (s == 0) {
    long long ret = (1LL << bitcount(x)) - 2;
    cout << ret << endl;
  } else {
    long long ret = (1LL << bitcount(x));
    cout << ret << endl;
  }
}

### Prompt

Your challenge is to write 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;
int bitcount(long long x) {
  int ret = 0;
  while (x) {
    if (x & 1) ++ret;
    x >>= 1;
  }
  return ret;
}
int main() {
  long long s, x;
  cin >> s >> x;
  if (s < x || (s - x) & 1 || ((((s - x) >> 1) & x) != 0)) {
    printf("0\n");
    return 0;
  }
  s -= x;
  s >>= 1;
  if (s == 0) {
    long long ret = (1LL << bitcount(x)) - 2;
    cout << ret << endl;
  } else {
    long long ret = (1LL << bitcount(x));
    cout << ret << endl;
  }
}

```