Module Module1

    Sub Main()

        Dim e As String
        Dim a, b, temp, ggt As Integer

        Console.WriteLine("Berechnung ggt ...")

        Console.WriteLine("a:")
        e = Console.ReadLine()
        a = Integer.Parse(e)

        Console.WriteLine("b:")
        e = Console.ReadLine()
        b = Integer.Parse(e)

        Console.WriteLine("a:" + Format(a) + " b:" + Format(b))

        If a <= 0 Or b <= 0 Then
            Console.WriteLine("Fehler: a>0 und b>0 gefordert.")
            Return
        End If

        While a <> b
            If b > a Then
                temp = a
                a = b
                b = temp
            End If
            a = a - b
        End While

        ggt = a
        Console.WriteLine("GGT: " + Format(ggt))




    End Sub

End Module