#include <bits/stdc++.h>
using namespace std;

int main() {
  int K;
  cin >> K;
  
  int p[] = {2, 3, 5, 7, 11, 13}, c[] = {4, 6, 8, 9, 10, 12}, m[36] = {};
  for (int i = 0; i < 6; ++i) {
    for (int j = 0; j < 6; ++j) {
      m[i * 6 + j] = p[i] * c[j];
    }
  }
  
  int ans = 0;
  for (int i = 0; i < 36; ++i) {
    if (m[i] == K) {
      ++ans;
    }
  }
  
  cout << fixed << setprecision(13) << ans / 36.0 << endl;
}