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