16
  0  0  0  4    7  0 10 15    0 12  9 16    2  5  0  0
  8  0 14 16    6  1  0  0    0 10  0  0    0  9  0 12
 15 10  0  0    9  5 14  8    1  7 13  0   16  0  0  0
  0  0 11  5    0  0  0  0    0  0  0  6    7  0  1 14

  4  0  0  0   16  0 15  5    0  6  0  0    0  8  0  2
 12 15  8  0   13  7  4  0   16  0  0  1    0  0  0  0
  5  0  0  0    0 10  0 14    8  0  0  0    0  0 12 13
  0 13 10  0    0  0  8  6   15  0  0  0    0  0  3  0

  0  0  4  0    0  0 13  0   11  3  0  0    9  0  0  0
  0  0  0 13   14  6  0 16    2  0  0 15    1  0  4  0
  0 11 15 14    1  0  0  0    0  0  0  0    6  0  0  0
  0 12  1  9   11  0  0  7    4 16  6  0   10  0  2  8

  0 16  0  0    0  4  0  0    7  0  0  0    8  0  9  0
 14  0  5  0    0  0  0  0   12 15  0  4    0  0  0  0
 11  4  0  3   15  0  7  0    0  0  0  8    0  1 16  0
  0  0  0  0    5  0 12 13    9  0  0  0   15 11 14  0