.MODEL SMALL
.STACK 100H
.DATA

   MSG DB 'ENTER YOUR NUMBER : $ '; 
   AA DB 10,13, 'Your Grade is: A $'
   BB DB 10,13, 'Your Grade is: B $'
   CC DB 10,13, 'Your Grade is: C $'
   EROR DB 10,13, 'YOUR INPUT VIOLATES $'
   NUM DB ?
   
.CODE 
   MAIN PROC
    MOV AX,@DATA
    MOV DS,AX
    
    MOV AH,9
    LEA DX,MSG
    INT 21H
       
    MOV AH,1
    INT 21H
    MOV NUM, AL
    
    
    CMP NUM,'3'
    JLE SEC1
    JG  SEC2
    
    SEC1:
        CMP NUM,'1'
        JGE A
        JL EXIT
        
        A:
        MOV AH,9
        LEA DX,AA
        JMP EXIT
        
    
     SEC2:
        CMP NUM,'6'
        JLE B
        JG  C
        
        B:
        MOV AH,9
        LEA DX,BB
        JMP EXIT          
           
        C:
        MOV AH,9
        LEA DX,CC
        JMP EXIT
    
    EXIT:
        ;INT 21H
        MOV AH,9
        LEA DX,EROR
        INT 21H     
           
    MOV AH,4CH
    INT 21H
     
   MAIN ENDP
END MAIN