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

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);  
	int a[6] = {2, 3, 5, 7, 11, 13};
	int b[6] = {4, 6, 8, 9, 10, 12};
	map<int, double> mp;
	for(int i = 0; i < 6; i++) {
		for(int j = 0; j < 6; j++) {
			mp[a[i] * b[j]]++;
		}
	}
	int k;
	cin >> k;
	cout << setprecision(20) << (double) mp[k] / (double) 36 << endl;
	return 0;	
}