#include <bits/stdc++.h>
using namespace std;
int a[] = { 2, 3, 5, 7, 11, 13 };
int b[] = { 4, 6, 8, 9, 10, 12 };
int n;
int main() {
	cin >> n;
	int ret = 0;
	for(int i = 0; i < 6; i++) {
		for(int j = 0; j < 6; j++) {
			if(a[i] * b[j] == n) ret++;
		}
	}
	cout << fixed << setprecision(15) << ret / 36.0 << endl;
	return 0;
}