#include<stdio.h>
int main()
{
	int k;
	scanf("%d", &k);
	int p[6] = { 2,3,5,7,11,13 }, g[6] = { 4,6,8,9,10,12 };
	int i, j, ans = 0;
	for (i = 0; i < 6; i++)
		for (j = 0; j < 6; j++)
			if (p[i] * g[j] == k)
				ans++;
	printf("%.20lf\n", (double)ans / 36.0);
	return 0;
}