#include <stdio.h>

int main() {
	int k, cnt = 0, i, j;
	int p[6] = { 2,3,5,7,11,13 };
	int c[6] = { 4,6,8,9,10,12 };

	scanf("%d", &k);

	for (i = 0; i < 6; i++) {
		for (j = 0; j < 6; j++) {
			if (p[i] * c[j] == k) cnt++;
		}
	}

	printf("%.13lf\n", cnt / 36.0);

	return 0;
}