Imports System

Public Module Module1

    Public Sub Main()

        Dim n1 as integer

        Dim sum as integer

        sum = 0

        Dim n2 as integer

        Dim n3 as integer

        dim n4 as integer

        Do

            n1 = console.ReadLine()

            n3 = n1

            n4 = (n3 - n2)

            if

                (n4 > 0) then

        loop until (n1 = -1)

    End Sub

End Module