4
   1   3   5   7
   3   2   4   6
   5   4   3   2
   7   6   2   9
   4
   4   0   0   0
   0   4   0   0
   0   0   4   0
   0   0   0   2
   4
   5   1   2   3
   4   5   6   7
   8   9  10  11
   9  13  14  10
   4
   5   1   2   3
   4   5   6   7
   8  10  12  13
   9  13  14  10
   4
   2  -1   0   0
  -1   2  -1   0
   0  -1   2  -1
   0   0  -1   2
   4