Edo get collection n refrigerator magnetsHe decide buy refrigerator hang magnet door the shop refrigerator size door meet follow restriction refrigerator door rectangle length width door positive integersEdo figure want place magnet refrigerator he introduce system coordinate plane magnet represent rectangle side parallel coordinate axesnow want remove k magnet choose attach remain magnet refrigerator door area door small possible a magnet consider attach refrigerator door center lie door boundary the relative position remain magnet correspond planlet explain sentence let suppose want hang magnet refrigerator if magnet plan coordinate lower left corner x1 y1 upper right corner x2 y2 center locate integer by say relative position correspond plan mean available operation translation ie vector connect center magnet original plan equal vector connect center magnet refrigeratorthe side refrigerator door parallel coordinate axis