Imports System

Public Module Module1

    Public Sub Main()

        dim op as char  

        DO 

            console.WriteLine("Enter (a)dd (s)ubtract (m)ultiply (d)ivide")

            op = console.readline()

        loop until op = "a" or op = "s" or op = "m" or op = "d" 

        console.writeline("at least you listen")        

    End Sub

End Module

​

'psudocode

'INTEGER : number

'

'REPEAT 

'   INPUT "enternumber from 1-4" , number

'UNTIL number >= 1 AND number <= 4

'

'OUTPUT : well listened