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