16
9
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|   |                                   |               |       |
+   +   +   +   +---+---+---+---+---+   +   +---+---+   +   +---+
|   |   |   |   |               |   |       |       |   |       |
+   +---+   +---+   +---+---+   +   +---+---+   +---+   +---+   +
|       |                   |   |       |           |   |       |
+---+   +---+---+---+---+---+   +   +   +   +---+   +   +   +   +
|   |   |                       |   |   |   |       |   |   |   |
+   +   +   +---+---+---+---+---+---+   +   +   +   +   +   +   +
|       |           |       |           |   |   |   |   |   |   |
+   +---+   +---+   +---+   +   +   +---+   +   +   +   +   +   +
|   |           |       |       |           |   |   |       |   |
+   +---+---+---+---+   +   +---+---+---+---+   +   +---+---+   +
|           |           |   |               |   |       |       |
+---+---+   +   +---+---+   +   +---+---+   +   +---+---+   +---+
|           |   |           |   |           |   |           |   |
+   +---+---+   +   +---+---+   +   +---+---+   +   +---+---+   +
|               |               |           |                   |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
