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