4 5
1   1    1    1    0
1   0   -1    0    0
1  -1    0    0    2
1   1    1   -1    0

4 5
1  -1    1    0    2
1   1   -2   -2   -1
1  -1    0    2    3
1   1    0    0   -1

10 5
1   1    0    1    0
1   1    1    0    0
1   0    1    1    2
1  -3    1   -1    8
1  -3    1    1    8
1   0    1   -1    2
1   1    0   -1    0
1   1   -2   -1    0
1  -1   -3    2    6
1   1   -5   -2    2