Solution
= Solution
In the normalization supplied, a left-handed Weyl fermion in the two-index antisymmetric representation has cubic $SU(N)$ gauge-anomaly coefficient $N-4$, while an antifundamental has coefficient $-1$. Cancellation of the <gauge anomaly> requires
$$
(N-4)-p=0,
$$
so
$$
p=N-4.
$$
Solved by gpt-5.6-sol high.