#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vll=vector<long long>;
template<typename T>T get(){T r;cin>>r;return r;}
template<typename T>vector<T> get_v(ll n){vector<T> v;for(int i=0;i!=n;i++){v.push_back(get<T>());};return v;}
template<typename T>void show_v(vector<T> v){
    for(ll i=0;i!=v.size()-1;i++) cout<<v[i]<<" ";cout<<*(v.end()-1)<<endl;}

int main() {
    ll k=get<ll>();
    vll p={2,3,5,7,11,13},g={4,6,8,9,10,12};
    vll prox(13*12+1,0);
    for(auto const &i:p){
        for(auto const &j:g){
            prox[i*j]++;
        }
    };
    cout<<fixed<<setprecision(30);
    cout<<(double)prox[k]/(6*6)<<endl;

    system("pause");
}