t0 = Y1+Y2
t1 = X1+X2
t2 = 1/t1
lambda = t0*t2
t3 = lambda^2
t4 = t3+lambda
t5 = t4+X1
t6 = t5+X2
X3 = t6+a2
t7 = X1+X3
t8 = lambda*t7
t9 = t8+X3
Y3 = t9+Y1