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]● ==> J6   [ 4]○ ==> G9   [ 5]● ==> H6
[ 6]○ ==> H9   [ 7]● ==> J9   [ 8]○ ==> G8   [ 9]● ==> J8   [10]○ ==> J7
[11]● ==> I7   [12]○ ==> G5   [13]● ==> K6   [14]○ ==> F9   [15]● ==> E9
[16]○ ==> I6   [17]● ==> H7   [18]○ ==> G7   [19]● ==> G6   [20]○ ==> G10
[21]● ==> G11  [22]○ ==> I8   [23]● ==> F11  [24]○ ==> K8   [25]● ==> H5
[26]○ ==> H4   [27]● ==> H12