xyst yxst xsyt sxyt ysxt syxt xyts yxts xtys txys ytxs tyxs xsty sxty xtsy txsy stxy tsxy ystx sytx ytsx tysx styx tsyx
Note: these 'words' (valid or invalid) are all the permutations of the word xyst. These words are obtained by scrambling the letters in xyst.