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

int main() {
  int K;
  cin >> K;
  double cnt = 0;
  vector<int> S(6), G(6);
  S = {2, 3, 5, 7, 11, 13};
  G = {4, 6, 8, 9, 10, 12};
  for (int i = 0; i < 6; i++)
    for (int j = 0; j < 6; j++)
      if (S.at(i) * G.at(j) == K) cnt++;

  cout << fixed << setprecision(12) << cnt / 36;
}