p, q, s, t, u, v, w, x, y, z, 
s*u
x*v
q*u
x*z
s*t*x+u*x
u*v^3-u*v*w+u*x
-p*u^2*v^2+p*u^2*w+q*t*x
t*x^2*y-u*v^2*z+u*w*z
