msd_4
0 0
0 -> 0
1 -> 1
2 -> 1
3 -> 2

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

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

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