Find the prime factorization in the DLP
As a hint, suppose we pick a random $h$, and compute $g = h^3 \bmod N$.  We then find the minimal value $x$ where $g^x \equiv h \pmod{N}$ (and, yes, such an $x$ will exist, assuming $p, q &gt; 7$).

What can we deduce from such a value of $x$?