#include <cstdio>
using namespace std;

int a[6] = {2, 3, 5, 7, 11, 13};
int b[6] = {4, 6, 8, 9, 10, 12};

int main() {
	int k;
	double ans = 0;

	scanf("%d", &k);
	for (int i = 0; i < 6; i++) {
		for (int j = 0; j < 6; j++) {
			if (a[i] * b[j] == k) {
				ans += 1 / 36.0;
			}
		}
	}
	printf("%.14f\n", ans);
	return 0;
}