/* -*- coding: utf-8 -*-
 *
 * 211.cc: No.211 素数サイコロと合成数サイコロ (1) - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int pds[6] = { 2, 3, 5, 7, 11, 13 };
const int cds[6] = { 4, 6, 8, 9, 10, 12 };

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int k;
  cin >> k;

  int cnt = 0;
  for (int i = 0; i < 6; i++)
    for (int j = 0; j < 6; j++)
      if (pds[i] * cds[j] == k) cnt++;

  printf("%.15lf\n", (double)cnt / 36);
  return 0;
}