#include <fstream.h>

int n,l,u,c[30001],t[30001],i;
double max;
long x,y;

main(){
	freopen("secv3.in", "r", stdin);
	freopen("secv3.out", "w", stdout);
	scanf("%d%d%d", &n, &l, &u);
	for(i=1;i<=n;i++)
		scanf("%d",&c[i]);
	for(i=1;i<=n;i++)
		scanf("%d",&t[i]);
	for(i=1;i<=l;i++){
		x+=c[i];
		y+=t[i];}
	max=x*1.0/y;
	for(i=l+1;i<=n;i++){
		x+=c[i]-c[i-l];
		y+=t[i]-t[i-l];
		if(x*1.0/y>max)
			max=x*1.0/y;}
	printf("%lf", max);}