var c,t,cl,tl:array[1..30000]of longint;
    l,u,n,i:longint;
begin
assign(input,'secv3.in');reset(input);
assign(output,'secv3.out');rewrite(output);
  readln(n,l,u);
  for i:=1 to n do read(c[i]);readln;
  for i:=1 to n do read(t[i]);
  cl[1]:=0;tl[1]:=0;
  for i:=1 to l do begin inc(cl[1],c[i]);inc(tl[1],t[i]);end;
  for i:=2 to n-l+1 do begin
    cl[i]:=cl[i-1]-c[i-1]+c[i+l-1];
    tl[i]:=tl[i-1]-t[i-1]+t[i+l-1];
  end;
  u:=1;
  for i:=2 to n-l+1 do
    if cl[u]/tl[u]<cl[i]/tl[i] then u:=i;
  write(cl[u]/tl[u]:2:2);
close(input); close(output);
end.