A B C D E F G H I J K L M N O
  15 ┌┬┬┬┬┬┬┬┬┬┬┬┬┬┐ 
  14 ├┼┼┼┼┼┼┼┼┼┼┼┼┼┤ 
  13 ├┼┼┼┼┼┼┼○┼┼┼┼┼┤ 
  12 ├┼┼┼┼┼┼●●┼┼┼┼┼┤ 
  11 ├┼┼┼┼┼┼○●○┼┼┼┼┤ 
  10 ├┼┼┼┼┼┼┼●●○●┼┼┤ 
   9 ├┼┼┼┼┼┼○○●○○○┼┤ 
   8 ├┼┼┼┼┼┼●○○●┼┼┼┤ 
   7 ├┼┼┼┼┼┼┼○┼●┼┼┼┤ 
   6 ├┼┼┼┼┼┼●●┼○┼┼┼┤ 
   5 ├┼┼┼┼┼┼┼┼●┼┼┼┼┤ 
   4 ├┼┼┼┼┼┼┼┼┼┼┼┼┼┤ 
   3 ├┼┼┼┼┼┼┼┼┼┼┼┼┼┤ 
   2 ├┼┼┼┼┼┼┼┼┼┼┼┼┼┤ 
   1 └┴┴┴┴┴┴┴┴┴┴┴┴┴┘ 

 [ 1]● ==> H8 [ 2]○ ==> H9   [ 3]● ==> J10  [ 4]○ ==> I9   [ 5]● ==> I11
 [ 6]○ ==> K9 [ 7]● ==> J9   [ 8]○ ==> J8   [ 9]● ==> K7   [10]○ ==> I7
 [11]● ==> L10[12]○ ==> J11  [13]● ==> I10  [14]○ ==> K10  [15]● ==> K8
 [16]○ ==> H11[17]● ==> I12  [18]○ ==> M9   [19]● ==> H12  [20]○ ==> I13
 [21]● ==> I6 [22]○ ==> L9   [23]● ==> H6   [24]○ ==> K6   [25]● ==> J5
 [26]○ ==> I8