0              0 
 0              1 
 0              2 
 0              3 
 1              0 
 1              1 
 1              2 
 1              3 
 2              0 
 2              1 
 2              2 
 2              3 
 3              0 
 3              1 
 3              2 
 3              3 
filled
 0 
 1 
 4 
 9