A B C D E F G H I J K L M N O
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  14 ├┼┼┼┼┼┼┼┼┼┼┼┼┼┤ 
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   1 └┴┴┴┴┴┴┴┴┴┴┴┴┴┘ 

 [ 1]● ==> H8  [ 2]○ ==> H9   [ 3]● ==> I6   [ 4]○ ==> I10  [ 5]● ==> I7
 [ 6]○ ==> G9  [ 7]● ==> G8   [ 8]○ ==> I8   [ 9]● ==> I9   [10]○ ==> H7
 [11]● ==> J10 [12]○ ==> G7   [13]● ==> J9   [14]○ ==> J8   [15]● ==> K9
 [16]○ ==> M9  [17]● ==> I11  [18]○ ==> L8   [19]● ==> K11  [20]○ ==> L12
 [21]● ==> J11 [22]○ ==> L11