var g,f:Text;
n,l,u,i,j,ss,dd,s,d:integer;
m:real;
v,b:array[1..100] of integer;
BEGIN
assign(f,'secv3.in');
reset(f);        readln(f,n,l,u);
for i:=1 to n do read(f,v[i]);
readln(f);
for i:=1 to n do read(f,b[i]);
close(F);

s:=0;
d:=0;
for i:=1 to l do
begin
s:=s+v[i];
d:=d+b[i];
end;
m:=s/d;
for i:=l+1 to n do
begin
        ss:=s;
        dd:=d;
        for j:=i to i+u-2 do
        begin
        ss:=ss+v[j];
        dd:=dd+b[j];
        if m<ss/dd then m:=ss/dd;
        end;
        s:=s+v[i]-v[i-u+1];
        d:=d+b[i]-b[i-u+1];
        if s/d>m then m:=s/d;
end;
assign(g,'secv3.out');
rewrite(g);
writeln(g,m:0:2);
close(g);


END.