+---+----+----+
         |   |  A |    |
         +---+----+----+
           |         |
           |         |
           v         |
    +---+----+----+  |
    |   |  B |    |  |
    +---+----+----+  |
      |              |
      |              |
      v              |
+--+----+----+       |
|  |  C |    | <-----+
+--+----+----+