add three number in assembly language

 .model small
 .stack 100h
 .code
 main proc
 
mov ah,1
int 21h
mov bh,al
int 21h
mov bl,al
int 21h
mov cl,al


add bh,bl
sub bh,48
add bh,cl
sub bh,48


mov ah,2
mov dl,0ah
int 21h
mov dl,0dh
int 21h

mov ah,2
mov dl,bh
int 21h
 
    mov ah,4ch
    int 21h

    main endp
 end main