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