#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>

using namespace std;


int main() {
	int i, j, k;
	vector<int>so = { 2,3,5,7,11,13 };
	vector<int>go = { 4,6,8,9,10,12 };


	cin >> k;

	int cnt = 0;

	for (i = 0; i < 6; i++) {
		for (j = 0; j < 6; j++) {
			if (k == so[i] * go[j])cnt++;
		}
	}

	double ritu = (double)cnt / (double)36 ;

	cout << fixed << setprecision(14) << ritu << endl;



	getchar();
	getchar();
	return 0;
}