#include <iostream>
#include <sstream>
#include <math.h>
#include <stack>
#include <set>
#include <algorithm>
#include <string>
#include <queue>
#include <stack>
#include <map>
#include <cstdio>
#include <vector>
#include <iomanip>
using namespace std;

#define INF (1 << 30)
#define INFLL (1LL << 60)

int main() {
	double ans = 0;
	int k;
	cin >> k;
	int s1[6] = {2,3,5,7,11,13};
	int s2[6] = {4,6,8,9,10,12};
	for(int i = 0;i < 6;i++){
		for(int j = 0;j < 6;j++){
			if(s1[i] * s2[j] == k) ans++;
		}
	}
	cout << fixed << setprecision(12);
	cout << ans / 36 << endl;
	return 0;
}