#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int,int>;
#define rep(i,n) for(int i=0;i<n;i++)

const ll mod = ll(1e9) + 7;
const int INF = 1<<29;

int main(){
    int k;
    cin >> k;
    vector<int> p = {2,3,5,7,11,13},np = {4,6,8,9,10,12};
    int cnt = 0;
    rep(i,6){
        rep(j,6){
            if (p[i]*np[j]==k) cnt++;
        }
    }
    printf("%.12lf",cnt/36.0);
    return 0;
}