+---+---+---+---+---+
| S                 |
+ v +---+---+---+   +
| v | > > > > v |   |
+ v + ^ +---+ v +   +
| v | ^ | E | v |   |
+ v + ^ + ^ + v +   +
| > > ^   ^ < <     |
+---+---+---+---+---+