20
12
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|                       |                       |   |       |           |       |
+---+---+---+---+   +---+   +---+   +---+   +   +   +   +---+   +   +---+   +---+
|       |                       |   |   |   |                   |       |       |
+---+   +   +---+   +   +---+   +---+   +---+---+---+---+---+---+---+   +   +---+
|               |   |       |   |           |           |   |           |       |
+   +---+---+---+---+---+---+   +   +   +   +   +---+   +   +   +   +---+   +   +
|               |           |       |   |   |   |   |       |   |           |   |
+   +---+---+   +   +---+   +   +   +---+---+   +   +---+---+   +---+---+---+---+
|   |               |       |   |       |           |           |       |       |
+   +   +---+---+---+   +---+   +   +---+   +---+---+---+---+---+   +---+---+   +
|   |   |       |   |       |   |   |                   |           |   |   |   |
+---+   +---+   +   +   +   +---+---+---+---+   +---+---+---+   +---+   +   +   +
|   |               |   |               |       |       |   |   |               |
+   +   +---+   +   +---+---+   +---+   +   +   +   +---+   +   +---+   +   +   +
|       |       |   |   |           |       |   |           |           |   |   |
+   +---+   +   +---+   +   +   +---+---+   +---+   +   +---+   +---+   +---+---+
|   |   |   |       |   |   |   |           |       |       |       |   |       |
+   +   +   +---+   +   +---+   +   +---+   +   +   +---+   +---+   +   +---+   +
|   |       |       |   |       |   |   |       |       |       |   |           |
+---+   +---+   +   +   +---+   +   +   +---+---+---+---+---+---+---+---+   +   +
|       |   |   |   |   |       |       |       |                           |   |
+---+   +   +   +---+   +   +---+---+---+   +   +   +   +   +---+---+---+---+   +
|           |           |                   |       |   |   |                   |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
