#include <bits/stdc++.h>
using namespace std;

signed main(){
  int A[6]={2,3,5,7,11,13};
  int B[6]={4,6,8,9,10,12};
  int k;cin>>k;
  long double ans=0;
  for(int i=0;i<6;i++)for(int j=0;j<6;j++)ans+=(A[i]*B[j])==k;
  ans/=36;
  cout<<fixed<<setprecision(15)<<ans<<endl;
}