2
 16      3       9         /
   \   / | \   / | \     5
     13  |   8   |   11  |
     |   14  |   7   |   12
     4     \ | /   \ | /   \
   /         10      6       15
 1


                             5
 9       3       15        /
   \   / | \   / | \     7
     13  |   2   |   11  |
     |   14  |   1   |   12
     8     \ | /   \ | /   \
   /         16      6      10
 4