0         1         2         3         4         5         6         7         8       
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  8 |         |         |         |         |         |         |         |         |         | 8
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  7 |         |         |         |         |         |         |         |         |         | 7
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  6 |         |         |         |         |         |         |         |         |         | 6
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  5 |         |         |         |         |         |         |         |         |         | 5
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  4 |         |         |         |         |         |         |         |         |         | 4
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  3 |         |         |         |         |         |         |         |         |         | 3
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  2 |         |         |         |         |         |         |         |         |         | 2
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  1 |         |         |         |         |         |         |         |         |         | 1
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
    |         |         |         |         |         |         |         |         |         |  
  0 |         |         |         |         |         |         |         |         |         | 0
    |         |         |         |         |         |         |         |         |         |  
    +---------+---------+---------+---------+---------+---------+---------+---------+---------+  
         0         1         2         3         4         5         6         7         8