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