Imports System

Public Module Module1

    Public Sub Main()

        Dim number as integer

        Dim op as string

        Do 

            Console.WriteLine("Please enter the number (1-4)")

            number = Console.ReadLine()

        Loop Until number >= 1 AND number <= 4

        Console.WriteLine("You listen to my command!")

        Console.Writeline("Please enter the operator (A)dd, (S)ubtract, (M)ultiple, (D)ivide")

            op = Console.ReadLine()

        Do while op <> "A" AND op <> "S" AND op <> "M" AND op <> "D"

            Console.Writeline("Please enter the operator (A)dd, (S)ubtract, (M)ultiple, (D)ivide")

            op = Console.ReadLine()

        Loop 

        Console.WriteLine("You listen to my command!")

    End Sub

End Module