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