#include <iostream>
#include <iomanip>
using namespace std;
int main(){
	int seki[36] = {8, 12, 12, 16, 18, 18, 20, 20, 24, 24, 27, 28, 30, 30, 36, 40, 42, 44, 45, 50, 52, 56, 60, 63, 66, 70, 78, 84, 88, 99, 104, 110, 117, 130, 132, 156};
	int k, ans = 0;
	cin >> k;
	for(int i = 0; i < 36; i++){
		if(seki[i] == k) ans++;
		if(seki[i] > k) break;
	}
	cout << setprecision(13) << (double)ans / 36 << endl;
}