#include <iostream>
using namespace std;

int main()
{
	const int p[] = { 2, 3, 5, 7, 11, 13 };
	const int c[] = { 4, 6, 8, 9, 10, 12 };
	int K, cnt = 0;
	cin >> K;
	for (int i = 0; i < 6; i++) {
		for (int j = 0; j < 6; j++) {
			if (p[i] * c[j] == K) cnt++;
		}
	}
	printf("%.15f\n", (double)cnt / 36);
	return 0;
}