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

int main() {
	int K;
	cin >> K;

	vector<int> vs = { 2,3,5,7,11,13 },
		vg = { 4,6,8,9,10,12 };
	int c = 0;
	for (int i = 0; i < 6; i++) {
		for (int j = 0; j < 6; j++) {
			if (vs.at(i) * vg.at(j) == K) c++;
		}
	}

	double a = c / 36.0;
	cout << fixed << setprecision(12) << a << endl;
}