#include <bits/stdc++.h>

using namespace std;
typedef long long ll;


int main(){
    int k;
    cin >> k;
    double q;
    int ans = 0;
    int c[6] = {2,3,5,7,11,13};
    int p[6] = {4,6,8,9,10,12};
    for (auto x : c)
        for (auto y : p)
            if (x * y == k)
                ans++;
    q = ans / 36.0;
    printf("%.15f\n" , q);

    return 0;
}