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