#include <iostream>
#include <cstdio>
#include <map>
using namespace std;

int main(void){
	int a[]={2,3,5,7,11,13};
	int b[]={4,6,8,9,10,12};
	std::map<int,int> m;
	double seki=6*6;
	for(int i=0;i<6;i++){
		for(int j=0;j<6;j++){
			m[a[i]*b[j]]++;
		}
	}
	int k;
	cin>>k;
	printf("%.12lf\n",(double)(m[k])/seki);
	return 0;
}