#include<iostream>
#include<string>
#include<algorithm>
#include<cmath>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include<cstring>
using namespace std;
 
int main(){

  int k, a[6]={2,3,5,7,11,13}, b[6]={4,6,8,9,10,12}, ans=0;
  cin >> k;

  for(int i=0; i<6; i++){
    for(int j=0; j<6; j++){
      if(k==a[i]*b[j]){
        ans++;
      }
    }
  }

  cout << setprecision(13);
  cout << ans/(double)36 << endl;

  return 0;
}