#include <stdio.h>

int main(void) {
	int i, j, K;
	int prime[] = {2, 3, 5, 7, 11, 13};
	int composite[] = {4, 6, 8, 9, 10, 12};
	int count = 0, total = 0;
	scanf("%d", &K);
	for(i = 0;i < 6;i++){
		for(j = 0;j < 6;j++){
			if(prime[i] * composite[j] == K)count++;
			total++;
		}
	}
	printf("%.13f\n", (double)count / total);

	return 0;
}