#include <vector>
#include <algorithm>
#include <cmath>
#include <fstream>
#define FOR(i,x) for (i=1;i<=x;++i)

using namespace std;

ifstream f("secv3.in");
ofstream g("secv3.out");

int st,dr,N,i,Sc,St,Mx,C[30001],T[30001];

int main()
{
    f>>N>>st>>dr;

    FOR(i,N) f>>C[i],C[i]=C[i]*100;

    FOR(i,N) f>>T[i];

    FOR(i,st-1) Sc+=C[i],St+=T[i];

    for (i=st;i<=N;++i)
        {
            Sc+=C[i]-C[i-st];
            St+=T[i]-T[i-st];

            if (Sc/St>Mx) Mx=Sc/St;
        }

    g<<Mx/100<<"."<<Mx%100/10<<Mx%10<<'\n';

    f.close();
    g.close();
    return 0;
}