SMO 2019 Problem 1

In the acute-angled triangle $ABC$ with circumcircle $\omega$ and orthocenter $H$ , points $D$ and $E$ are the feet of the perpendiculars from $A$ onto $BC$ and from $B$ onto $AC$ respecively. Let $P$ be a point on the minor arc $BC$ of $\omega$ . Points $M$ and $N$ are the feet of the perpendiculars from $P$ onto lines $BC$ and $AC$ respectively. Let $PH$ and $MN$ intersect at $R$ . Prove that $\angle DMR=\angle MDR$ .