#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int ans = 0;
  vector<int> A={2,3,5,7,11,13},B={4,6,8,9,10,12};
  int N;
  cin>>N;
  for(int i=0;i<6;i++)for(int j=0;j<6;j++) if(A[i]*B[j] == N) ans++;
  cout<<fixed<<setprecision(15);
  cout<<ans*1.0/36<<endl;
}