#include <bits/stdc++.h>
using namespace std;
 
int main(){
  int K;
  cin>>K;
  int P[6]={2,3,5,7,11,13};
  int G[6]={4,6,8,9,10,12};
  int count=0;
  for(int i : P){
      for(int j : G){
          if(i*j==K){
              count++;
          }
      }
  }
  printf("%.13lf",(double)count/36);
  cout<<endl;
}