(assert (= x0 -3))
(assert (= x1 -4))
(assert (= x2 -3))
(assert (= x3 -3))
(assert (= x4 -4))
(assert (= x5 0))
(assert (= x6 1))
(assert (= x7 -2))
(assert (= x8 1))
(assert (= x9 1))