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

int main() {
  int K; cin >> K;
  vector<int> A = {2, 3, 5, 7, 11, 13};
  vector<int> B = {4, 6, 8, 9, 10, 12};
  int con = 0;
  for(int i = 0; i < 6; i++){
    for(int j = 0; j < 6; j++){
      if(K == A[i]*B[j]) con++;
    }
  }
  double ans = con / 36.0;
  cout << setprecision(15) << ans << endl;
}