#include <iostream>
#include <algorithm>
#include <vector>
#include <array>
#include <cstdio>
using namespace std;

int main(){
	int k;
	cin >> k;
	array<int,6> so{2,3,5,7,11,13};
	array<int,6> go{4,6,8,9,10,12};
	int count = 0;
	for(int i = 0; i < 6; i++){
		for(int j = 0; j < 6; j++){
			if(k == so[i] * go[j]) count++;
		}
	}
	printf("%.100lf\n",double(count/36.0));
	return 0;
}