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