#include <bits/stdc++.h>
using namespace std;
void pairsort(int a[], int b[], int n) {
  pair<int, int> pairt[n];
  for (int i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (int i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
void pairsortlli(long long int a[], long long int b[], long long int n) {
  pair<long long int, long long int> pairt[n];
  for (long long int i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (long long int i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
long long int binomialCoeff(long long int n, long long int k) {
  long long int C[k + 1];
  memset(C, 0, sizeof(C));
  C[0] = 1;
  for (long long int i = 1; i <= n; i++) {
    for (long long int j = min(i, k); j > 0; j--)
      C[j] = (C[j] + C[j - 1]) % 1000000007;
  }
  return C[k];
}
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
long long int max(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int min(long long int a, long long int b) {
  if (a < b) return a;
  return b;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long int s, x;
  cin >> s >> x;
  if (abs(s - x) % 2 == 1 || s < x)
    cout << 0 << "\n";
  else {
    long long int p;
    long long int a = (s - x) / 2;
    if (s == x)
      p = 2;
    else
      p = 0;
    long long int q = 1;
    while (x != 0) {
      if (x % 2) {
        q *= 2;
        if (a % 2 == 1) {
          cout << 0 << "\n";
          return 0;
        }
      }
      a /= 2;
      x /= 2;
    }
    cout << q - p << "\n";
  }
}

### Prompt

Construct a Cpp code solution to the problem outlined:

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 pairsort(int a[], int b[], int n) {
  pair<int, int> pairt[n];
  for (int i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (int i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
void pairsortlli(long long int a[], long long int b[], long long int n) {
  pair<long long int, long long int> pairt[n];
  for (long long int i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (long long int i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
long long int binomialCoeff(long long int n, long long int k) {
  long long int C[k + 1];
  memset(C, 0, sizeof(C));
  C[0] = 1;
  for (long long int i = 1; i <= n; i++) {
    for (long long int j = min(i, k); j > 0; j--)
      C[j] = (C[j] + C[j - 1]) % 1000000007;
  }
  return C[k];
}
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
long long int max(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int min(long long int a, long long int b) {
  if (a < b) return a;
  return b;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long int s, x;
  cin >> s >> x;
  if (abs(s - x) % 2 == 1 || s < x)
    cout << 0 << "\n";
  else {
    long long int p;
    long long int a = (s - x) / 2;
    if (s == x)
      p = 2;
    else
      p = 0;
    long long int q = 1;
    while (x != 0) {
      if (x % 2) {
        q *= 2;
        if (a % 2 == 1) {
          cout << 0 << "\n";
          return 0;
        }
      }
      a /= 2;
      x /= 2;
    }
    cout << q - p << "\n";
  }
}

```