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