4 4
0 0 1
0 1 2
0 2 0
0 3 0
1 0 4
1 1 7
1 2 2
1 3 1
2 0 3
2 1 8
2 2 5
2 3 0
3 0 7
3 1 4
3 2 7
3 3 3
-1 -1 -1