#include<stdio.h>

int main(void){
	int i,j,x,a[8]={2,3,5,7,11,13},b[8]={4,6,8,9,10,12},n[256]={0};
	for(i = 0;i <= 5;i++){for(j = 0;j <= 5;j++){n[(a[i]*b[j])]++;}}
	double r;
	scanf("%d",&x);
	r = n[x];
	printf("%.16lf",r/36);
	return 0;
}