.MODEL SMALL
.STACK 100H
.DATA 
.CODE
MAIN PROC
    MOV AH,1H
    int 21H                                     
    MOV BH,AL
    INT 21H
    
    MOV BL,AL
    INT 21H 
   
   MOV CL,AL
   ADD BH,BL
    SUB BH,CL
    
    MOV AH,2H

    MOV DL,bh
    INT 21H  
    MOV AH,4CH
    INT 21H
    
    
MAIN ENDP
END MAIN