const n=10;
type mas=array[1..n]of integer;
var a,b:mas;
i:integer;
function max(a:mas):integer;
var i,m:integer;
begin
m:=a[1];
for i:=2 to n do
if a[i]>m then m:=a[i];
max:=m;
end;
procedure res;
var x:real;
begin
x:=(max(a)*max(b))/(max(a)+max(b));
writeln(x:0:3);
end;
begin
randomize;
for i:=1 to n do
begin
a[i]:=random(21)-10;
b[i]:=random(11)-5;
write(a[i]:4);
end;
writeln;
for i:=1 to n do
write(b[i]:4);
writeln;
res;
readln;
end.