there infinite board square tile initially tile whitevova red marker blue marker red marker color tile blue marker color b tile if tile is not white can not use marker color each marker drain completely end exactly red tile exactly b blue tile boardvova want color set tile form rectangle consist exactly ab colored tile tile color form rectangle here example correct coloring here example incorrect coloring among correct coloring Vova wants choose minimal perimeter what minimal perimeter Vova obtainit guarantee exist correct coloring