1  0 <?> 0  0 --> 1
1  1 <?> 0  0 --> 0
1  4 <?> 0  0 --> 0
1  4 <?> 1  4 --> 1
0  4 <?> 1  4 --> 1
0  1 <?> 1  4 --> 0
0  4 <?> 1  4 --> 1