dseg segment para public "data"
                buff db 7,8 dup ("?")
                promt db "=xy"
                out2 db "Your number is: $"
                error db "incorrect number$"
        number equ 34
dseg ends

...

Input proc far
                mov bp,bx
                mov ah,02 ; Promt for input
                mov bx, offset promt
                mov dl,[bx+si+1]
                int 21h

                mov dl,[bx]
                int 21h

                mov ah,0ah ; Take string
                mov dx,offset buff
                int 21h