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