Imports System

Public Module Module1

    Public Sub Main()

        Dim x As Integer

        Console.WriteLine("Please enter the student mark")

        x = Console.ReadLine()

        select case x

        case x>80

            Console.WriteLine("The student grade is A")

        case x>70

            Console.WriteLine("The student grade is B")

        case x>60

            Console.WriteLine("The student grade is C")

        case x>50

            Console.WriteLine("The student grade is D")

        End Select

    End Sub

End Module