Let n be a positive integer. Each cell of a 2n×2n square is painted in one of the 4n2 colors (with some colors may be missing). We will call any two-cell rectangle a domino[/I], and a domino is called colorful[/I] if its cells have different colors. Let k be the total number of colorful dominoes in our square; l be the maximum integer such that every partition of the square into dominoes contains at least l colorful dominoes. Determine the maximum possible value of 4l−k over all possible colourings of the square. combinatoricsColoringdominoes