 15
                            
                                        15              
                            
                            
                     
                                                 8               
                            
                                        3D ture
                            
                                        8               
                            
                                        3D ture
                            
                     
                                                 9
                            
                                        9               
                            
                            
                     
                                                 2
                            
                                        2               
                            
                            
                     
                                                 16
                            
                                        16              
                            
                            
                     
                                                 6
                            
                                        6               
                            
                            
                     
                                                 9
                            
                                        9               
                            
                            
                     
                                                 2
                            
                                        2               
                            
                            
                    