#include <bits/stdc++.h>
using namespace std;
long long s, x;
long long tm, tj;
int T[80], ok, sz;
int main() {
  scanf("%lld%lld", &s, &x);
  if (s == x) ok = 2;
  int log = max(log2(x), log2(s));
  for (int i = 0; i <= log; i++) {
    if ((x & ((long long)1 << i)) == 0)
      T[sz++] = i + 1;
    else
      tm++, tj += ((long long)1 << i);
  }
  s -= x;
  for (int i = sz - 1; i >= 0; i--)
    if (s - ((long long)1 << T[i]) >= 0) s -= ((long long)1 << T[i]);
  long long B = ((long long)1 << tm);
  B *= (s == 0);
  B -= ok;
  printf("%lld\n", B);
}

### 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;
long long s, x;
long long tm, tj;
int T[80], ok, sz;
int main() {
  scanf("%lld%lld", &s, &x);
  if (s == x) ok = 2;
  int log = max(log2(x), log2(s));
  for (int i = 0; i <= log; i++) {
    if ((x & ((long long)1 << i)) == 0)
      T[sz++] = i + 1;
    else
      tm++, tj += ((long long)1 << i);
  }
  s -= x;
  for (int i = sz - 1; i >= 0; i--)
    if (s - ((long long)1 << T[i]) >= 0) s -= ((long long)1 << T[i]);
  long long B = ((long long)1 << tm);
  B *= (s == 0);
  B -= ok;
  printf("%lld\n", B);
}

```