=begin
a = gets.to_i
s = gets

if a < 3200
  puts "red"
else
  puts s
end
=end

=begin
b = gets.to_i
a = gets.split(" ").map{|x| x.to_f}
sum = 0.0
b.times do |i|
  sum += 1/a[i]
end
p 1 / sum
=end

n = gets.to_i
a = gets.split(" ").map{|x| x.to_f}

while true
  a.sort!
  a.push((a[0] + a[1]) / 2.0)
  a.delete_at(0)
  a.delete_at(0)
  break if a.size == 1
end
