A B C D E F G H I J K L M N O
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  1 └┴┴┴┴┴┴┴┴┴┴┴┴┴┘
[ 1]● ==> H8   [ 2]○ ==> I9   [ 3]● ==> J8   [ 4]○ ==> I8   [ 5]● ==> I7
[ 6]○ ==> H6   [ 7]● ==> J6   [ 8]○ ==> K5   [ 9]● ==> J7   [10]○ ==> J9
[11]● ==> H7   [12]○ ==> G7   [13]● ==> K7   [14]○ ==> L7   [15]● ==> I5
[16]○ ==> H4   [17]● ==> K9   [18]○ ==> K8   [19]● ==> I10  [20]○ ==> H10
[21]● ==> G8   [22]○ ==> F9   [23]● ==> K11  [24]○ ==> L10  [25]● ==> J11
[26]○ ==> H9   [27]● ==> G9   [28]○ ==> F10  [29]● ==> I11