/   \  @  / |    |    |
|    |    |  \   /     \   /     \   /  |    |    |
|    |L_11|   \ /   o y \ / x o   \ /   |L_00|    |
|    o---------o    |    o    |    o---------o    |
|         |     \ x @   / \   @ y /     |         |
|         |      \     /   \     /      |         |
|         |       \   /     \   /       |         |
|         |L_10    \ /   o   \ /    L_01|         |
|         o---------o    |    o---------o         |
|                    \   @   /                    |
|                   