#include<bits/stdc++.h>

using namespace std;

const int NMAX = 30000;
int price[NMAX+1],timp[NMAX+1];
double ans;
int main()
{
    ifstream cin("secv3.in");
    freopen("secv3.out","w",stdout);
    int n,l,u;
    cin>>n>>l>>u;
    for(int i=1;i<=n;++i)
    {
        cin>>price[i];
        price[i]+=price[i-1];
    }
    for(int i=1;i<=n;++i)
    {
        cin>>timp[i];
        timp[i]+=timp[i-1];
    }
    ans=price[l]*1.0/timp[l];
    int poz=1;
    double a,b;
    for(int i=l+1;i<=n;++i)
    {
        if(i-l==u)
            poz++;
        a=(price[i]-price[i-l])*1.0/(timp[i]-timp[i-l]);
        b=(price[i]-price[poz-1])*1.0/(timp[i]-timp[poz-1]);
        if(a>b)
        {
            b=a;
            poz=i-l+1;
        }
        if(ans<b)
            ans=b;
    }
    printf("%.2lf",ans);
    return 0;
}