284_A. Cows and Primitive Roots_8798
The cows have just learned what a primitive root is! Given a prime p, a primitive root <image> is an integer x (1 ≤ x < p) such that none of integers x - 1, x2 - 1, ..., xp - 2 - 1 are divisible by p, but xp - 1 - 1 is. 

Unfortunately, computing primitive roots can be time consuming, so the cows need your help. Given a prime p, help the cows find the number of primitive roots <image>.

Input

The input contains a single line containing an integer p (2 ≤ p < 2000). It is guaranteed that p is a prime.

Output

Output on a single line the number of primitive roots <image>.

Examples

Input

3


Output

1


Input

5


Output

2

Note

The only primitive root <image> is 2.

The primitive roots <image> are 2 and 3.
#include <bits/stdc++.h>
using namespace std;
int main() {
  int p;
  cin >> p;
  int t;
  int flag = 0;
  int ans = 0;
  for (int i = 1; i < p; i++) {
    t = i;
    for (int j = 1; j <= p - 2; j++) {
      if ((t - 1) % p != 0) {
        t = (t % p) * i;
      } else {
        flag = 1;
        break;
      }
    }
    if (flag == 0 && (t - 1) % p == 0) {
      ans++;
    }
    flag = 0;
  }
  cout << ans;
}
