#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU

N = gets.to_i

A = gets.chomp.split.map(&:to_i).sort

if N.odd?
	puts A[N.div(2)]
else
	puts (A[N.div(2).pred].to_f + A[N.div(2)].to_f)./(2)
end