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