Imports System

Public Module Module1

    Public Sub Main()

        dim A1 as TimeSpan

        dim A2 as TimeSpan

        A1 = TimeSpan.Parse("19:00:00")

        A2 = TimeSpan.Parse("07:00:00")

        if A2 < A1 then

            A2 = A2 + TimeSpan.Parse("01:00:00:00")

        end if

        While A1 <= A2

            Console.WriteLine(A1.toString())

            A1 = A1 + TimeSpan.Parse("00:30:00")

        end while

    End Sub

End Module