Rough Dentogram ( clustering based on segment distance )

   PE 66  74  
   !  
   8--PE  9  18  
   !     
   1-----PE 55  59  
   !        
   6--------PL 51  54  
   !           
   5-----------PH 40  50  
   !              
   4--------------PH  2   8  
   !                 
   !                 PL 33  39  
   !                 !  
   2-----------------3--PH 19  32  
   !                       
   7-----------------------PL 60  65  
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