#2

6x6
1 0 0 0 0 0
1 1 0 0 0 0
0 -1 1 0 0 0
0 0 -1 1 0 0
0 0 0 -1 1 1
0 0 0 0 -1 1

6x6
0 0 0 0 -1 0
0 0 0 0 0 -1
0 1 1 0 1 0
1 0 0 -1 0 0
-1 0 0 -1 0 -1
0 -1 1 0 0 0

dim6/4-1;2-1a

