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