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