grade sheet

FOR x = 1 TO 4
    READ y$
    PRINT y$
    PRINT "quiz"
    INPUT q1
    IF q1 > 0 AND q1 < 16 THEN
        PRINT "assignment"
    ELSE
        PRINT "you have put wrong mark"
        PRINT "start again"
    END IF
    INPUT a1
    IF a1 > 0 AND a1 < 21 THEN
        PRINT "mid"
    ELSE
        PRINT "you have put worng number"
    END IF
    sum = q1 + a1
    avrg = sum / 2
    DATA "enter mark of CF"
    DATA "enter mark of Eng"
    DATA "enter mark of ISE"
    DATA "enter mark of AOL"
NEXT x