type vector=array [1..20] of record
                             c,t:integer
                             end;
procedure citire(var a:vector;var n,l,m:integer);
var i:integer;
f:text;
begin
assign(f,'in3.txt');reset(f);
while not eof(f) do begin
read(f,n,l,m);
for i:=1 to n do read(f,a[i].c);
for i:=1 to n do read(f,a[i].t)
end;
close (f)end;
procedure ver(a:vector;n,l,u:integer);
var i,j,r,s1,s2:integer;
max:real;
begin
max:=0;
for i:=1 to n do begin
s1:=0;s2:=0;r:=0;
for j:=i to i+u-1 do begin
inc(r);
s1:=s1+a[j].c;
s2:=s2+a[j].t;
if r>=l then if s1/s2>max then max:=s1/s2;
end end;
write(max:4:2)
end;
var a:vector;
    n,u,i,l:integer;
    begin
    citire(a,n,l,u);
    ver (a,n,l,u);
    readln;end.