#include <bits/stdc++.h>

using namespace std;
int pdice[6] = {2, 3, 5, 7, 11, 13};
int cdice[6] = {4, 6, 8, 9, 10, 12};
int K;
int main(){
  cin >> K;
  int res = 0;
  for (int i = 0; i < 6; i++){
    for (int j = 0; j < 6; j++){
      int num = pdice[i] * cdice[j];
      if (num == K){
	res++;
      }
    }
  }
  printf("%.20Lf\n", (long double)res / 36.0);
}