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