#include <stdio.h>
#include <algorithm>
#include <deque>
using namespace std;
using ll = long long;

//211
int main() {
	int k, a[6] = { 2, 3, 5, 7, 11, 13 }, b[6] = { 4, 6, 8, 9, 10, 12 };
	scanf("%d", &k);

	double p = 0.0;
	for (int i = 0; i < 6; i++)
		for (int j = 0; j < 6; j++)
			if (a[i] * b[j] == k)
				p += 1;
	printf("%.12lf\n", p / 36);
}