0	 0 0 0 0 0 0 0 0
     1	 0 0 1 0 0 1 0 0
     2	 0 0 1 2 2 1 0 0
     3	 0 0 1 2 3 4 5 5
     4	 0 0 1 2 3 4 5 6
     5	 0 1 2 3 3 2 0 1
     6	 0 1 2 3 3 2 1 0
     7	 0 1 2 3 4 5 6 6
     8	 0 1 2 3 4 5 6 7