#include<iostream>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<numeric>

int main() {
	std::vector<int> composit{ 4, 6, 8, 9, 10, 12 };
	std::vector<int> prime{ 2, 3, 5, 7, 11, 13 };

	std::vector<int> perhaps((14 * 13 + 1), 0);

	for (std::vector<int>::iterator it = composit.begin(); it != composit.end(); it++) {
		for (std::vector<int>::iterator it2 = prime.begin(); it2 != prime.end(); it2++) {
			perhaps[(*it) * (*it2)]++;
		}
	}

	double total = std::accumulate(perhaps.begin(), perhaps.end(), 0.0);

	int num;
	std::cin >> num;

	std::cout << std::fixed << std::setprecision(16) << 
		perhaps[num] / total << std::endl;

	return 0;
}