0 --> 1: 1
0 --> 2: 2
1 --> 0: 2
1 --> 3: 1
2 --> 2: 1
3 --> 1: 1

0 --- 1: 1
0 --- 2: 2
1 --- 3: 1
2 --- 2: 1

0 --- 1: 2
2 --- 2: 1
1 --- 3: 1

0 --- 1: 1
1 --- 3: 1
2 --- 2: 1

0 --- 1: 2
0 --- 2: 2
1 --- 3: 1
2 --- 2: 1

0 --- 1: 3
0 --- 2: 2
1 --- 3: 2
2 --- 2: 1