#include <iostream>
#include <algorithm>
#include <vector>
#include <deque>
#include <string>
#include <tuple>
#include <functional>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <map>
#include <random>
//#include "toollib.h"
#define INT_MAX 2147483647
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#pragma warning (disable:4018)

using namespace std;
typedef long long int lint;

//***** Main Program *****

int main() {
	vector<int> a{ 2,3,5,7,11,13 }, b{ 4,6,8,9,10,12 };
	int K;
	cin >> K;
	int ret = 0;
	Loop(i, 6) {
		Loop(j, 6) {
			if (a[i] * b[j] == K) ret++;
		}
	}
	cout << setprecision(15) << ret / 36.0 << endl;
	return 0;
}