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(a - 1) As Double
        For i As Integer = 0 To a - 1
            val(i) = Double.Parse(arr(i))
        Next i
        Array.Sort(val)
        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