0                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    2                                    
                                        
                                            
                                    1                                    
                                        
                                            
                                    2                                    
                                        
                                            
                                    3                                    
                                        
                                            
                                    2                                    
                                        
                                            
                                    4