− v 4 u 4 + v 3 u 4 + v 4 u 3 − 3 v 3 u 3 + 2 v 2 u 3 + 2 v 3 u 2 − 3 v 2 u 2 + 2 v u 2 + 2 v 2 u − 3 v u + u + v − 1 {\displaystyle -v^{4}u^{4}+v^{3}u^{4}+v^{4}u^{3}-3v^{3}u^{3}+2v^{2}u^{3}+2v^{3}u^{2}-3v^{2}u^{2}+2vu^{2}+2v^{2}u-3vu+u+v-1}
