Indian National Mathematics Olympiad 2004 Problems

Indian National Mathematics Olympiad 2004 Problems1.  ABCD is a convex quadrilateral. K, L, M, N are the midpoints of the sides AB, BC, CD, DA. BD bisects KM at Q. QA = QB = QC = QD, and LK/LM = CD/CB. Prove that ABCD is a square.