A                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                      A to C
                                                                                                                                                                                            
                                                                                                                                                                                            
                                   A to B                                                                                                                                   C               
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                            condition?                                                      
                                                                                                                                                                                            
                          B                                                                                                                                                                 
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                   B to E                                                                                                                                   D               
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                          E                                                                                                                                                                 
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                   E to G                                                                                                                                                   
                                                                                                                                                                            F               
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                      F to G
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                                                                                            
                                                                                                                               G