#include <stdio.h>

int memo[201];

int main(void) {
	int n;
	scanf("%d", &n);
	int a[6] = {2, 3, 5, 7, 11, 13};
	int b[6] = {4, 6, 8, 9, 10, 12};
	int i, j;
	for(i = 0; i < 6; i++) {
	for(j = 0; j < 6; j++) {
		memo[ a[i] * b[j] ]++;
	}
	}
	printf("%.12f\n", memo[n] / 36.0 );
	return 0;
}