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

int p[] = {2, 3, 5, 7, 11, 13};
int c[] = {4, 6, 8, 9, 10, 12};

int main() {
	int K;
	cin >> K;
	double ans = 0;
	for(int i = 0; i < 6; i++) {
		for(int j = 0; j < 6; j++) {
			if(K == p[i] * c[j]) ans++;
		}
	}
	ans /= 36;
	cout << fixed << setprecision(15) << ans << endl;
	return 0;
}