#include <iostream>
#include <vector>
#include <iomanip>
using namespace std;

vector<int> p={2,3,5,7,11,13};
vector<int> c={4,6,8,9,10,12};

int main(){
  int k;
  cin>>k;
  double x;
  x=0;
  for(int i=0; i<6; ++i){
    for(int j=0; j<6; ++j){
      double a;
      a=p[i]*c[j];
      if(k==a){
        x++;
        break;
      }
    }
  }
  double y;
  y=x/36;
  cout<<fixed<<setprecision(15)<<y<<endl;
  return 0;
}