Typo in the full interactive protocol in Figure 1 of Halo paper?

[3for]

I'm reading the Halo paper, in Figure 1 of page 17, I think the v9 val should be r(x,y)(xy)^{3N-1}.

[3for]

r(X,1) has exponents of X that span from X^{-2N} to X^{N}， why we choose to multiply 3N-1 in the paper？ Is it proper to multiply 2N instead？