#include<stdio.h>
long n,mi,ma,i,aa,a[30050],b[30050],j;
double x,x1,x2;
int main()
{
 freopen("secv3.in","r",stdin);
 freopen("secv3.out","w",stdout);
 scanf("%ld%ld%ld",&n,&mi,&ma);
 for(i=1;i<=n;++i)
    scanf("%ld",&aa),a[i]=a[i-1]+aa;
 for(i=1;i<=n;++i)
    scanf("%ld",&aa),b[i]=b[i-1]+aa;
 x=(double)a[mi]/b[mi];
 j=1;
 for(i=mi+1;i<=n;++i)
    {if(i-j+1>ma)++j;
     x1=(double)(a[i]-a[j-1])/(b[i]-b[j-1]);
     x2=(double)(a[i]-a[i-mi])/(b[i]-b[i-mi]);
     if(x1<x2){j=i-mi+1;x1=x2;}
     if(x<x1)x=x1;}
 printf("%.3lf\n",x);
 return 0;
}