#include<iostream>
#include <math.h>
#include <string>
using namespace std;

int main(){
	int s[6] = { 2, 3, 5, 7, 11, 13 };
	int g[6] = { 4, 6, 8, 9, 10, 12 };
	int k;
	int cnt = 0;
	
	cin >> k;
	for (int i1 = 0; i1 < 6; i1++){
		for (int i2 = 0; i2 < 6; i2++){
			if (s[i1] * g[i2] == k){
				cnt += 1;
			}if (s[i1] * g[i2] > k){
				break;
			}	
		}
	}
	//cout << cnt << endl;
	//long double resalt =1.0* cnt / 36.0;
	cout.precision(15);
	cout << (long double)cnt/36 << endl;
	return 0;
}