---

.model small
.stack 100h

.data

n dw 49

.code

start:

    mov ax, @data
    mov ds, ax

    mov cx, n
    mov bx, 1

m1:

    mov ax, bx
    mul bx

    cmp ax, n
    je found

    inc bx

    loop m1

    mov ax, 0
    jmp finish

found:

    mov ax, bx

finish:

    mov ah, 4Ch
    int 21h

end start