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