Demonstrate how to find a solution to a given [[wp:Sokoban|Sokoban]] level. For the purpose of this task (formally, a PSPACE-complete problem) any method may be used. However a move-optimal or push-optimal (or any other -optimal) solutions is preferred.

Sokoban levels are usually stored as a character array where
* ''space'' is an empty square
* # is a wall
* @ is the player
* $ is a box
* . is a goal
* + is the player on a goal
* * is a box on a goal

Sokoban solutions are usually stored in the LURD format, where lowercase l, u, r and d represent a move in that ('''l'''eft, '''u'''p, '''r'''ight, '''d'''own) direction and capital LURD represents a push.

Please state if you use some other format for either the input or output, and why.

For more information, see [http://www.sokobano.de/wiki/index.php?title=Main_Page the Sokoban wiki].