#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max
#include <string>	//string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt
#include <sstream>	//stringstream,getline
#include <cmath>	//ceil

using namespace std;

int main() {

	int A[6] = { 2,3,5,7,11,13 };
	int B[6] = { 4,6,8,9,10,12 };

	int K;
	cin >> K;

	long double temp = 0;

	for (int i = 0; i < 6; i++) {
		for (int j = 0; j < 6; j++) {
			if (A[i] * B[j] == K) {
				temp++;
			}
		}
	}

	long double ans = temp / 36;
	cout << fixed << setprecision(12) << ans << endl;

	return 0;

}