#include<iostream>
using namespace std;


int main()
{
	int num[] = { 2,3,5,7,11,13 };
	int num2[] = { 4,6,8,9,10,12 };
	int K;
	cin >> K;
	int count = 0;
	for (int i = 0;i < 6;i++) {
		for (int j = 0;j < 6;j++) {
			if (num[i] * num2[j] == K) {
				count++;
			}
		}
	}
	double ans = ((double)count) / 36.0;
	cout << ans;
	return 0;
}