+------+  |    |  o  |   |  +---+   
|         |    |     |\ /|  |   |
|       --+----+  |  | Y |  +---+
|         |    |  |  |   |  |
+-------+ |    |  |  |   |  |

+     +   +--  \      /          |
|     |   |     \    /  /\       |
+-----+   +---   \  /  /  \      |
      |   |       \/  /----+    
      |   +-----     /      \    0