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

int main() {
    int K, ans = 0;
    cin >> K;
    int A[6] = {2, 3, 5, 7, 11, 13}, B[6] = {4, 6, 8, 9, 10, 12};
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 6; j++) {
            if (A[i] * B[j] == K)
                ans++;
        }
    }

    cout << fixed << setprecision(13) << ans / 36.0 << endl;
}