#include<iostream>
using namespace std;
int main(){
	int sosuu[] = { 2, 3, 5, 7, 11, 13 };
	int gousei[] = { 4, 6, 8, 9, 10, 12 };
	int k, count = 0;
	cin >> k;
	for (int i = 0; i < 6; i++){
		for (int j = 0; j < 6; j++){
			count += (sosuu[i] * gousei[j] == k);
		}
	}
	printf("%.12lf\n", ((double)count / 36));
	return 0;
}