# your code goes here

n=STDIN.gets.to_i
as=STDIN.gets.split(" ")


as.size.times do |i|
	as[i]=as[i].to_i
end
as=as.sort()

if n%2==1 
	puts as[n/2]
else
	puts (as[n/2-1]+as[n/2])/2.0
end