.text
	mov	R3, #1	;starting at two
doover:
	add	R3, R3, #1 ; r3++
	mul	R4, R3, R3
	cmp	R4, R1  ; is r4 >= r2?
	beq	itsperfect
	bgt	itsnot
	blt	doover

itsperfect:
	mov	R2, R3
	swi	#h00900001

itsnot:
	mov	R2, #0
	sub	R2, R2, #1
	swi	#h00900001