module Resistors_in_Parallel
  sub Main(ByVal args() as String)
    dim a as integer
    a=Console.ReadLine()
    dim arr(a-1) as string
    arr=Split(Console.ReadLine())
    dim val as new List(of double)
    for i as integer = 0 to a-1
    val.add(double.parse(arr(i)))
  next i
  val.sort
  for i = 0 to a-2
  val(i+1)=(val(i)+val(i+1))/2
next i
    
    Console.WriteLine(val(val.Count))
  end sub
end module