−3z4a−2−2z4a−4−8z2a−2−z2a−4 + 3z2a−6 + 3z2−10a−2 + 4a−4 + 2a−6−a−8 + 5−5a−2z−2 + 4a−4z−2−a−6z−2 + 2z−2