2. In an acute triangle $\triangle ABC$, $H$ is the orthocenter, and $O$ is the circumcenter. The perpendicular bisector of $CH$ intersects $AC$ and $BC$ at points $X$ and $Y$, respectively. The lines $XO$ and $YO$ intersect $AB$ at points $P$ and $Q$, respectively. If $XP + YQ = AB + XY$, find $\angle OHC$.