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