checkers

                                                                                                                        
                                                                                                                        
                                                                                                                        
                                                                                                                        
                                                                                                                        
                                                                                                                        
                          M                                   M                                                         
                          M                                   M                                                         
                M M M     M M M         M M         M M M     M     M     M M       M   M     M M M                     
              M       M   M     M     M     M     M       M   M   M     M     M     M M     M                           
              M           M     M     M M M M     M           M M M     M M M M     M         M M                       
              M       M   M     M     M           M       M   M     M   M           M             M                     
                M M M     M     M       M M M       M M M     M       M   M M M     M       M M M