This Ain't Your Grandpa's Checkerboard

This problem gives you a specification for a board of white and black squares and asks if it is "valid," where valid means each row and column independently has the same number of white and black squares, and there are no more than 3 white or black squares in a row in any row or column. This is simply walking through the input and checking the specified conditions, as the maximum grid is only 24x24