12
8
+---+---+---+---+---+---+---+---+---+---+---+---+
|               |               |   |           |
+   +---+---+   +   +   +   +---+   +   +---+   +
|           |       |   |               |       |
+---+   +---+   +   +   +---+---+---+---+   +---+
|   |   |       |   |   |   |           |       |
+   +---+   +   +---+   +   +---+   +---+---+---+
|           |   |                       |       |
+---+   +---+---+   +---+---+---+---+   +---+   +
|           |               |       |       |   |
+   +---+---+   +---+   +---+   +---+---+---+   +
|   |       |   |   |                   |       |
+---+---+   +   +   +---+---+---+   +---+---+   +
|           |                   |           |   |
+   +   +   +   +---+---+---+---+   +---+---+   +
|   |   |                       |               |
+---+---+---+---+---+---+---+---+---+---+---+---+
