#include <iostream>
#include <iomanip>
using namespace std;
 
int main(){
	int K;
	cin >> K;
	int primes[6] = {2, 3 ,5, 7, 11, 13};
	int synthesis[6] = {4, 6, 8, 9, 10, 12};
	int ans = 0;
	for(int i = 0; i < 6; i++){
		for(int j = 0; j < 6; j++){
			if(K == primes[i] * synthesis[j]){
				ans++;
			}
		}
	}
	cout << setprecision(20) << ans / 36.0 << endl;
}