#define _USE_MATH_DEFINES

#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin
#include <ios>			//fixed
#include <iomanip>		//setprecision
#include <sstream>		//stringstream
#include <numeric>		//gcd, assumlate
#include <random>		//randam_device
#include <limits>		//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	vector<int> A = { 2,3,5,7,11,13 };
	vector<int> B = { 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 (A[i] * B[j] == K) {
				cnt++;
			}
		}
	}

	double ans = cnt / 36.0;
	cout << fixed << setprecision(14) << ans << endl;

	return 0;

}