#include <iostream>
#include <vector>

using namespace std;

int main(){

	std::vector<int> sosu{2,3,5,7,11,13};
	std::vector<int> gose{4,6,8,9,10,12};
	
	int k;
	cin >> k;
	int res = 0;	
	for(int i=0; i<7; i++){
		for(int t=0; t<7; t++){
			if(sosu[i]*gose[t] == k){
				res++;
				break;
			}
			if(sosu[i]*gose[t] > k) break;
		}
	}
    float kakuritu = (float)res / (float)36.0;
	printf("%.12lf", kakuritu);
	cout << endl;

	return 0;
}