10
7
+---+---+---+---+---+---+---+---+---+---+
|               |           |       |   |
+---+---+   +---+---+---+   +   +   +   +
|               |       |   |   |   |   |
+   +---+---+   +   +   +   +---+   +   +
|           |       |                   |
+   +---+---+   +   +   +---+   +---+---+
|           |   |   |       |       |   |
+   +---+---+   +   +---+   +---+   +   +
|   |   |       |   |       |           |
+   +   +   +---+   +---+---+---+---+---+
|   |       |       |       |   |       |
+   +   +---+   +---+   +---+   +   +---+
|   |       |                           |
+---+---+---+---+---+---+---+---+---+---+
