/* fibonacci */

/* F_0 = 0 */
/* F_1 = 1 */
/* F_n = F_{n-1} + F_{n-2} */

struct a b c end;

method fib(x)
	if x < 0 then return x; end;
	a := 0;
	if x < 1 then return x; end;
	b := 1;
	if x < 2 then return x; end;
	var t := this;

	while not (x < 2)
	do
		t.c := t.a-(0-t.b);
		t := t--8;
		x := x-1;
	end;
	return (t-8).c;
end;