10
7
+---+---+---+---+---+---+---+---+---+---+
|       |                   |       |   |
+---+   +   +---+   +---+   +   +---+   +
|       |       |       |       |       |
+   +---+---+---+---+   +   +---+---+   +
|           |           |               |
+---+---+   +   +---+---+---+---+   +---+
|       |           |   |       |       |
+---+   +   +---+   +   +   +---+---+   +
|               |           |           |
+   +   +---+   +   +---+---+---+   +---+
|   |       |   |   |           |       |
+   +---+   +---+---+---+---+   +   +---+
|   |                       |           |
+---+---+---+---+---+---+---+---+---+---+
