#include <iostream>
#include <cstdio>
using namespace std;
int main(){
	int sosu[]={2,3,5,7,11,13};
	int gousei[]={4,6,8,9,10,12};
	int k;	cin>>k;
	int cnt=0;
	for(int i=0;i<6;i++){
		for(int j=0;j<6;j++){
			if(sosu[i]*gousei[j]==k)	cnt++;
		}
	}
	printf("%.17lf\n",(double)cnt/36);
	return 0;
}