^                     t                                                       
  |                     t                                                       
  |            t        t  t                                         t          
  |            t  t     t  t  t                                      t          
  |   t     t  t  t  t  t  t  t                                      t          
  |   t  t  t  t  t  t  t  t  t  t                                   t          
  |   t  t  t  t  t  t  t  t  t  t  t                          t  t  t  t       
  |   t  t  t  t  t  t  t  t  t  t  t  t r                     t  t  t  t       
  |  rt  t  t  t  t  t  t  t  t  t  t  t rt                    t  t  t  t  t    
  |  rt rt rt  t  t  t rt  t  t  t  t  t rt rt r         t  t  t  t  t  t  t    
 -+---------------------------------------------------------------------------> 
  |  12 13 14 15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11