2. In the acute $\triangle A B C$, take a point $P$ such that
$$
\angle P A C=60^{\circ}, \angle P C A=\angle P B A=30^{\circ} \text {, }
$$
$M 、 N$ are the midpoints of sides $A C 、 B C$ respectively. Then the degree of $\angle P N M$ is $\qquad$