P :=
9 5
1   3   1  -3  -1
1   0  -1   0   5
1   0   0   1   0
1  -1   0   1   1
1  -6  -1   5  11
1   0   0  -1   1
1   0  -1   0   1
1   1   0   0  -1
1   0   1   0   0

;
assert((card P) = { 5 });
