#include <iostream>
#include <fstream>
#include <vector>
#include <deque>
#include <iomanip>
using namespace std;
ifstream in ("secv3.in");
ofstream out("secv3.out");
struct tl
{
    int p1, p2;
    tl(int i=0, int j=0) {
        p1=i; p2=j;
    }
    friend tl operator + (const tl ths, const tl that) {
        return {ths.p1+that.p1, ths.p2+that.p2};
    }
    friend tl operator - (const tl ths, const tl that) {
        return {ths.p1-that.p1, ths.p2-that.p2};
    }
    void operator +=(const tl that) {
        p1+=that.p1; p2+=that.p2;
    }
    void operator -=(const tl that) {
        p1-=that.p1; p2-=that.p2;
    }

    operator double() {
        return (double)p1/p2;
    }

    friend bool operator <=(tl ths, tl that){
        return ths.p1*that.p2<=ths.p2*that.p1;
    }

};

int n, l1, l2, stact, dract;
vector <tl> a;
tl act;
double maxi=0;
inline tl getInterval(int st, int dr)
{
    if(dr<st)
        return {0, 0};
    return a[dr]-a[st-1];
}
int main()
{
    in>>n>>l1>>l2;
    a.resize(n+1);
    for(int i=1; i<=n; i++)
        in>>a[i].p1;
    for(int i=1; i<=n; i++)
        in>>a[i].p2;
    for(int i=2; i<=n; i++)
        a[i]+=a[i-1];

    stact=1; dract=l1; act=a[l1];

    maxi=act;

    for(int i=l1+1; i<=l2; i++)
    {
        //cout<<"q";
        if(act<=a[i])
        {
            act=a[i];
            maxi=act;
            dract=i;
        }
    }
    for(int i=2; i<=n-l1+1; i++)
    {
        act-=getInterval(i-1, i-1);
        stact++;

        if(dract-stact+1<l1)
        {
            dract++; act+=getInterval(dract, dract);
        }

        if(act<=(act+getInterval(dract+1, min(i+l2-1, n))))
        {
            act=(act+getInterval(dract+1, min(i+l2-1, n)));
            dract=min(i+l2-1, n);
        }
        if(maxi<=(double)act)
            maxi=act;
    }
    out<<fixed<<setprecision(2)<<maxi;
    return 0;
}