(define (add-to-end lst x)
	(if (null? lst)
		(list x)
		(cons (car lst) 
			  (add-to-end (cdr lst) x))))





(define (fact n)
	(if (<= n 1)
		1
		(* n (fact (- n 1)))))

(define (fact-tail n)
	(define (helper n total)
		(if (= n 0)
			total
			(helper (- n 1) (* total n))))
	(helper n 1))