#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>
#include <limits>
#include <iomanip>
using namespace std;

int main(){


  long double ans=0;
  int k; cin >> k;
  vector<int> x,y;
  x = {2, 3, 5, 7, 11, 13};
  y = {4, 6, 8, 9, 10, 12};

  for (int i = 0; i < 6; i++) {
    for (int j = 0; j < 6; j++) {
      int a = x[i] * y[j];
      if (a == k) {
        ans++;
      }
    }
  }
  cout << setprecision(numeric_limits<double>::max_digits10) << ans / 36 << "\n";
  return 0;
}