#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <sstream>
#include <complex>
#include <algorithm>
#include <functional>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <cmath>
#include <cassert>
#include <fstream>
#define REP(i,n) for(int i=0;i<n;i++)
#define FOR(a,b) for(:a<b;a++)
#define SSTR( x ) static_cast< std::ostringstream & >( \
        ( std::ostringstream() << std::dec << x ) ).str()
#define ALL(s) (s).begin(), (s).end()
using namespace std;
typedef long long unsigned int llu;
typedef long long ll;

const string D_blue    = "\x1b[36m";
const string D_green   = "\x1b[32m";
const string D_red     = "\x1b[31m";
const string D_yellow  = "\x1b[33m";
const string Db_red    = "\x1b[41m";
const string Db_yellow = "\x1b[43m";
const string D_end     = "\x1b[39m";
const string Db_end    = "\x1b[49m";
							     
int main (){
  int k;

  int dice[2][6] = {{2,3,5,7,11,13},{4,6,8,9,10,12}};
  
  while (cin >> k){
    vector<int> vi;
    REP(i,6){
      if(k % dice[0][i] == 0){
	vi.push_back(k / dice[0][i]);
      }
    }
    int cnt = 0;
    REP(i,vi.size()){
      REP(j,6){
	if(vi[i] == dice[1][j]){
	  cnt++;
	}
      }
    }
    double ans = (double)cnt / (double)36;
    printf("%.13f\n" , ans);
  }
  return 0;
}