a7z−1−3za5−a5z−1 + a5z−3 + 3z3a3−4a3z−1−3a3z−3−z5a + z3a + 5za + 7az−1 + 3az−3 + 2z3a−1−za−1−3a−1z−1−a−1z−3−za−3