Sub main()
        Dim mark As Integer
        Console.WriteLine(“Enter marks of student.”)
        mark = Console.ReadLine()
        Console.WriteLine(“The mark is {0}.” & grade(mark))
        Console.ReadLine()
    End Sub
    Function grade(ByVal mark As Integer) As String
        Select Case mark
            Case Is >= 80
                grade = "A"
            Case Is >= 70
                grade = "B"
            Case Is >= 60
                grade = "C"
            Case Is >= 50
                grade = "D"
            Case Is >= 40
                grade = "E"
            Case Else
                grade = "F"
        End Select