{$N+}
const coll=250000;
var n,i,j:longint;
m:array[0..coll] of double;


procedure Go(li,ls:longint);
var
  i,j:longint;
  x,y:double;
begin
i:=li;
j:=ls;
x:=m[(li+ls) div 2];

repeat
while m[i]<x do inc(i);
while m[j]>x do dec(j);

 if i<=j then
      begin
        x:=m[i];
        m[i]:=m[j];
        m[j]:=x;
        inc(i);
        dec(j);
      end;

until i>j;

if i<ls then Go(i,ls);
if j>li then Go(li,j);

end;

begin
readln(n);
for i:=1 to n do readln(m[i]);
Go(1,n);

if n=1 then writeln(m[1]:1:1)
   else if n mod 2=1 then writeln(m[n div 2+1]:1:1)
   else writeln((m[n div 2]+m[n div 2+1])/2:1:1);
end.


help plz