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