0: 0, 1
0: 4, 5
0: 4, 6
0: 5, 6
0: 7, 8
0: 7, 9
0: 8, 9
0: 10, 11
0: 10, 12
0: 10, 13
0: 10, 14
0: 11, 12
0: 11, 13
0: 11, 14
0: 12, 13
0: 12, 14
0: 13, 14
0: 18, 19
1: 0, 2
1: 1, 2
1: 4, 7
1: 4, 8
1: 4, 9
1: 5, 7
1: 5, 8
1: 5, 9
1: 6, 7
1: 6, 8
1: 6, 9
1: 10, 15
1: 11, 15
1: 12, 15
1: 13, 15
1: 14, 15
1: 15, 16
1: 17, 18
1: 17, 19
2: 2, 3
2: 3, 4
2: 3, 5
2: 3, 6
2: 10, 16
2: 11, 16
2: 12, 16
2: 13, 16
2: 14, 16
2: 16, 17
6