no                                                                     yes                                    
                                                                                                         x?                                                                         
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                            A                                                                                                                                      B
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                         yes                                                                                                        
                                      y?                                                                                                                                            
                                                     no                                                                                                                             
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                            C                                                                                                                                       
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                               D                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                                                                                                    
                                                                                                               E