http://cs.marlboro.edu/~eholder/cgi/ex/tiles/ulwall.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/exup.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/urwall.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/exleft.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/center.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/exright.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/dlwall.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/exdown.gif
http://cs.marlboro.edu/~eholder/cgi/ex/tiles/drwall.gif
9
-1
-1
2
0