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

int main(){
    int K;
    vector<double> v;
    int pn[] = {2,3,5,7,11,13}, cn[] = {4,6,8,9,10,12};

    for(int i=0;i<6;i++){
        for(int j=0;j<6;j++){
            v.push_back(pn[i]*cn[j]);
        }
    }
    cin >> K;
    int sum=0;
    for(int i=0;i<v.size();i++){
        if(v[i]==K) sum++;
    }
    printf("%.12f\n", (double)sum/36);
    

    return 0;
}