1    2             3         4      5    
                          
        6               7    8     
  9     10                       
       11                     
                   12         
  13        14                    
                          
             15               
 16     17    18                      
                          
19                   20    21         
    22                        
                          
 23                24             
           25    26               
                          
    27            28              
                   29         
        30                    
                          
    31                        
                          
          32