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