#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<vector>
#include<string.h>
#include<math.h>
#include<map>
#include<iomanip>
#include<queue>

const long long INF = 1e6+7;
const long long MOD = 1e9+7;
const double PI=acos(-1);

using namespace std;

int main(){
	int k;
	cin >> k;
	vector<int> s={2,3,5,7,11,13};
	vector<int> g={4,6,8,9,10,12};
	int cnt=0;
	for(int i=0;i<6;i++){
		for(int j=0;j<6;j++){
			if(s[i]*g[j]==k){
				cnt++;
			}
		}
	}
	double ans=(double)cnt / 36;
	cout << fixed << setprecision(15) << ans << endl;
	return 0;
}