
7 7

0 2 3 4 -1 0 0
0 3 4 2 0 -1 0
1 1 0 0 0 0 0
1 0 1 0 0 0 0
1 0 0 1 0 0 0
1 0 0 0 1 0 0
1 0 0 0 0 1 0

2
