CHECKER 4 4
[0,0,1,0,0,2] [1,0,2,0,1,2] [2,0,3,0,3,1] [3,0,4,0,3,1]
[3,1,2,2,3,2]
[0,2,-1,2,1,3] [1,2,0,2,1,3] [2,2,1,2,3,3] [3,2,2,2,3,3]
[1,3,0,4,1,4] [3,3,2,4,3,4]