import algorithm, sequtils, strutils
 
var
  n = parseInt readLine stdin
  a = stdin.readLine.split.map parseFloat
 
a.sort cmp
var n2 = n div 2
 
if n mod 2 == 0:
  echo (a[n2] + a[n2 - 1]) / 2
else:
  echo a[n2]