#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;
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;

    maxi=0;

    for(int i=l1; i<=l2; i++)
        if(maxi<=(double)getInterval(1, i))
            dract=i, maxi=(double)getInterval(1, i);

    for(int i=1; i<=n-l1+1; i++)
    {
        if(dract-i+1<l1)
            dract++;

        int drpos=min(i+l2-1, n);

        if(getInterval(i, dract)<=getInterval(i, drpos))
            dract=drpos;

        maxi=max(maxi, (double)getInterval(i, dract));
    }
    out<<fixed<<setprecision(2)<<maxi;
    return 0;
}