#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define fr(i, a, b) for (int i = (a); i < (b); i++)
#define all(c) (c).begin(), (c).end()
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

int main() {
    int a[] = {2,3,5,7,11,13};
    int b[] = {4,6,8,9,10,12};

    double ans = 0;

    int K;
    cin >> K;

    rep (i, 6) {
        rep (j, 6) {
            if (a[i] * b[j] == K) {
                ans += 1;
            }
        }
    }

    ans /= 36;

    printf("%.15f\n", ans);
}