A = X2*X3 B = Z2*Z3 t0 = A^2 t1 = B^2 t2 = a6*t1 X5 = t0+t2 t3 = X2+Z2 t4 = X3+Z3 t5 = t3*t4 t6 = t5-A t7 = t6-B t8 = t7^2 Z5 = X1*t8