RU-ALLRUSSIAN 2012 Problem 93

Consider the parallelogram $ABCD$ with obtuse angle $A$ . Let $H$ be the feet of perpendicular from $A$ to the side $BC$ . The median from $C$ in triangle $ABC$ meets the circumcircle of triangle $ABC$ at the point $K$ . Prove that points $K,H,C,D$ lie on the same circle.