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