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