#include <bits/stdc++.h>
using namespace std;
int primes[] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47};
int phi(int n) {
  int num = 1, root = (int)sqrt(n), *prime = primes, Phi = n, N = n;
  for (; *prime <= root && n != 1; prime++)
    if (!(n % *prime)) {
      Phi = Phi / (*prime) * (*prime - 1);
      for (; !(n % *prime); n /= *prime, num *= *prime)
        ;
    }
  if (num != N) {
    num = N / num;
    Phi = Phi / num * (num - 1);
  }
  return Phi;
}
int main() {
  int p;
  while (scanf("%d", &p) != EOF) printf("%d\n", phi(phi(p)));
  return 0;
}
