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