#include<bits/stdc++.h>
using namespace std;
int main(){
    int k,pat=0;
    cin>>k;
    vector<int> a={2,3,5,7,11,13},b={4,6,8,9,10,12};
    for(int i=0;i<6;++i){
        for(int j=0;j<6;++j){
            if(k==a[i]*b[j])++pat;
        }
    }
    double ans=pat/36.0;
    cout<<fixed<<setprecision(17)<<ans<<endl;
}