#include <iomanip>
#include <iostream>

using namespace std;

int main(int argc, const char* argv[])
{
	int K;
	cin >> K;
	int ca[] = {2, 3, 5, 7, 11, 13};
	int cb[] = {4, 6, 8, 9, 10, 12};
	int sum  = 0;
	for (auto&& a : ca)
		for (auto&& b : cb) sum += a * b == K;
	cout << fixed << setprecision(12) << (double)sum / 36.0 << endl;
	return 0;
}