−z6a−2−z6a−4−5z4a−2−4z4a−4 + z4a−6 + z4−9z2a−2−2z2a−4 + 4z2a−6 + 4z2−10a−2 + 4a−4 + 2a−6−a−8 + 5−5a−2z−2 + 4a−4z−2−a−6z−2 + 2z−2