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

int main() {
	int P[6] = { 2, 3, 5, 7, 11, 13 }, C[6] = { 4, 6, 8, 9, 10, 12 }, K;
	map<int, double> mp;
	cin >> K;
	for (int i = 0; i < 6; i++) {
		for (int j = 0; j < 6; j++) {
			mp[P[i] * C[j]] ++;
		}
	}
	double X = mp[K] / 36.0;
	printf("%8f", X);
}