#include <bits/stdc++.h>
using namespace std;
void kehsihba() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
void solve() {
  long long s, x;
  cin >> s >> x;
  long long dif = (s - x);
  if (dif % 2 == 1 or s < x or (s - x) / 2 & x) {
    cout << 0;
    return;
  }
  long long ans = __builtin_popcountll(x);
  ans = 1ll << ans;
  if (s == x) {
    ans -= 2;
  }
  cout << ans;
}
int32_t main() {
  kehsihba();
  long long t = 1;
  for (long long k = 1; k <= t; k++) {
    solve();
  }
}

### Prompt

In cpp, your task is to solve 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;
void kehsihba() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
void solve() {
  long long s, x;
  cin >> s >> x;
  long long dif = (s - x);
  if (dif % 2 == 1 or s < x or (s - x) / 2 & x) {
    cout << 0;
    return;
  }
  long long ans = __builtin_popcountll(x);
  ans = 1ll << ans;
  if (s == x) {
    ans -= 2;
  }
  cout << ans;
}
int32_t main() {
  kehsihba();
  long long t = 1;
  for (long long k = 1; k <= t; k++) {
    solve();
  }
}

```