2017  2  13
                
          
  3   
                     
                   
                   
                          
                             
                    
                             
                     
                             
                              
                      
                             
                              
                            
                           
                           
                              
  4   
                  
                          
                           
                          
                            
                 
                            
                             
 5    
                 
                            
                 
                         
 6     
                 
                  
7   
                  

         