10
-9 4 -9 7
-8 0 1 0
-1 8 -1 -10
-10 -6 -5 -6
-9 -1 4 -1
-7 3 -6 3
-3 4 0 4
9 -10 9 6
10 -5 10 -2
1 -5 -4 -5