#include<iostream>
#include<cstdio>
#include<map>
#include<iomanip>
using namespace std;

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

	map<int, double> mp;
	int a[6] = { 2,3,5,7,11,13 };
	int b[6] = { 4,6,8,9,10,12 };
	for (int i = 0; i < 6; i++)
	{
		for (int j = 0; j < 6; j++)
		{
			mp[a[i] * b[j]] += 1;
		}
	}
	cout << fixed << setprecision(17) << mp[k] / 36 << endl;

	return 0;
}