8
5
+---+---+---+---+---+---+---+---+
|   |       |                   |
+   +   +---+---+   +---+---+   +
|               |   |       |   |
+   +---+   +---+---+   +---+   +
|       |   |       |   |       |
+   +---+---+   +---+   +   +---+
|           |   |       |       |
+   +   +---+   +   +---+   +---+
|   |                           |
+---+---+---+---+---+---+---+---+
