#include <bits/stdc++.h>

int main() {
  double ans = 0;

  int a[6] = { 2, 3, 5, 7, 11, 13 };
  int b[6] = { 4, 6, 8, 9, 10, 12 };
  int K;

  std::cin >> K;

  for(int i = 0; i < 6; ++i) {
    for(int j = 0; j < 6; ++j) {
      if( a[i] * b[j] == K ) {
	ans += 1.0;
      }
    }
  }

  ans /= 36;

  printf("%.12lf\n", ans);

  return 0;
}