#include <iostream>
#include <cstdio>
#define X 30001
using namespace std;
int n,l,u,i,j,nr;
double rez,a,b,c[X],t[X];

int main()
{
    freopen("secv3.in","r",stdin);
    freopen("secv3.out","w",stdout);
    scanf("%d %d %d\n",&n,&l,&u);
    for(i=1; i<=n; i++)
    {

        scanf("%d ",&nr);
        c[i]=c[i-1]+nr;

    }
    scanf("\n");
    for(i=1; i<=n; i++)
    {
        scanf("%d ",&nr);
         t[i]=t[i-1]+nr;
    }
     rez=c[l]/t[l];
    j=1;
    for(i=l+1;i<=n;i++)
    {
        if(i-l==u)
            j++;
        a=(c[i]-c[j-1])/(t[i]-t[j-1]);
        b=(c[i]-c[i-l])/(t[i]-t[i-l]);
        if(a<b)
        {
            a=b;
            j=i-l+1;
        }
        rez=max(rez,a);

    }
    printf("%.2lf ",rez);

    return 0;
}