Welcome to SWI-Prolog (Multi-threaded, 64 bits, Version 6.6.6)
Copyright (c) 1990-2013 University of Amsterdam, VU Amsterdam
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to redistribute it under certain conditions.
Please visit http://www.swi-prolog.org for details.

For help, use ?- help(Topic). or ?- apropos(Word).


true.

Stack: [50,1,1,2,30,11,43,12]
Result: [1,1,2,11,12,30,43,50]; OK
true.


% halt