A                                                                                                                                    
                                      A                                                                                                                                    
                                      A                                                                                                                                    
                                      AA                                                                                                                                   
                                                                                                                                                                           
                                      A                                                                                                                                    
                                      AA                                                                       B                                                           
                                      A                                                                                                                                    
                                      A                                                                                                                                    
                                      A                                                                                                                                  CA
                                      AA                                                                                                                                   
                                      A                                                                   bb                                                               
                                      AA                                                                                                                                   
                                                                                                                                                                           
                                                                                                                                                                           
                                                                                                                                                                     ccc   
                                                                                                                                                                           
                                                                                                                                                                           
                                           a