#include <iostream>
#include <iomanip>

using namespace std;

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

	double count = 0.0;

	const int a[6] = {2, 3, 5, 7, 11, 13};
	const int 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) ++count;
		}
	}

	cout << fixed << setprecision(15) << (count / 36.0) << endl;
}