#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  vector<int> prime = {2, 3, 5, 7, 11, 13};
  vector<int> composite = {4, 6, 8, 9, 10, 12};
  map<int, int> mp;
  for (int p : prime) {
    for (int c : composite) {
      mp[p * c]++;
    }
  }
  int K;
  cin >> K;
  cout << fixed << setprecision(12) << mp[K] / 36.0 << '\n';
  return 0;
}