7 7

1   0   0  1  0  0  -1
1   0   0 -1  0  1   0
1   1  -1  0  0  0   0
1  -1   0  0  1  0  -1
0   0   1 -1  0  0   0
1   0   0  0 -1  1   0
0   1   1 -1  1 -1   0

0 6

