##
my %adjacency_list = (
1 => [2,5,6],
2 => [1,3,5,6,7],
3 => [2,4,6,7,8],
4 => [3,7,8],
5 => [1,2,6,9,10],
6 => [1,2,3,5,7,9,10,11],
7 => [2,3,4,6,8,10,11,12],
8 => [3,4,7,11,12],
9 => [5,6,10,13,14],
10 => [5,6,7,9,11,13,14,15],
11 => [6,7,8,10,12,14,15,16],
12 => [7,8,11,15,16],
13 => [9,10,14],
14 => [9,10,11,13,15],
15 => [10,11,12,14,16],
16 => [11,12,15]
);
##
##
1,2,3
1,2,5
1,2,6
1,2,7
1,5,2
1,5,6
...
16,15,14,13,10,11