{$APPTYPE CONSOLE}
var
m:array[0..250000] of longword;
n,size,i:longint;
res:extended;
newel:longword;
child:longint;
t:longword;

procedure downHeap(k,n:longint);
begin
newel:=m[k];
while(k<=n) do begin
child:=2*k+1;
if(child<n)and(m[child]<m[child+1]) then inc(child);
if(newel>=m[child])or(child>n) then break;
m[k]:=m[child];
k:=child;
end;
m[k]:=newel;
end;

procedure HeapSort;
begin
for i:=(size-1) div 2 downto 0 do downHeap(i,size-1);

i:=size;
while(i>0) do begin
dec(i);
t:=m[i];
m[i]:=m[0];
m[0]:=t;
downHeap(0,i-1);
end;
end;

begin
readln(size);
for i:=0 to size-1 do readln(m[i]);
HeapSort;
n:=size;
if n mod 2=1 then begin res:=m[((n+1)div 2)-1]; write(res:0:1) end else begin
res:=m[n div 2-1];
res:=res+m[n div 2];
res:=res/2;
write(res:0:1);
end;
end.