#include<iostream>
#include<iomanip>
using namespace std;
int main(void)
{
	int n[6] = { 2,3,5,7,11,13 }, p[6] = { 4,6,8,9,10,12 }, i, k, j, s=0;
	
	cin >> k;
	for (i = 0; i < 6; i++) {
		for (j = 0; j < 6; j++) {
			if (k == n[i] * p[j])
				s++;
		}
	}

	cout << fixed << setprecision(15) << (double)s/36 << endl;

	return 0;
}