.MODEL SMALL
.STACK
.DATA
    msg   db 'input max?$'
    msg1  db '1+2+...+$'
    odoa  db 0dh,0ah,'$'
    t1    db ?
    tt    db ?
    tab   db '0123456789'
.CODE
    MOV   AX,@DATA
    MOV   DS,AX
;
    lea   dx,msg
    mov   ah,09
    int   21h
;
    mov   ah,01
    int   21h
    mov   tt,al
;
    lea   dx,odoa
    mov   ah,09
    int   21h
;
    lea   dx,msg1
    mov   ah,09
    int   21h
    mov   dl,tt
    mov   ah,02
    int   21h
    mov   dl,'='
    mov   ah,02
    int   21h
;
    mov   cl,tt
    sub   cl,'0'
    sub   ch,ch
    xor   dx,dx
    mov   bx,1
aa: add   dx,bx
    inc   bx
    loop  aa
    mov   ax,dx
    xor   dx,dx
    mov   cl,10
    div   cl
;
    mov   t1,ah    ; quotient is al, remainder is ah
    add   al,30h
    mov   dl,al
    mov   ah,02
    int   21h
;
    mov   dl,t1
    add   dl,30h
    mov   ah,02
    int   21h
;
    mov   ah,4ch
    int   21h
END