As written, the Domineering program does not verify that a player has chosen a valid location. A player may place a domino so that it overlaps an existing one. Also, if the player places a domino so...

As written, the Domineering program does not verify that a player has chosen a valid location. A player may place a domino so that it overlaps an existing one. Also, if the player places a domino so that part of it is off the board, the program will crash. Modify the program to fix both these problems. (If the player enters invalid coordinates, give her a chance to enter valid ones.)