satfw astfw stafw tsafw atsfw tasfw saftw asftw sfatw fsatw afstw fastw stfaw tsfaw sftaw fstaw tfsaw ftsaw atfsw tafsw aftsw fatsw tfasw ftasw satwf astwf stawf tsawf atswf taswf sawtf aswtf swatf wsatf awstf wastf stwaf tswaf swtaf wstaf twsaf wtsaf atwsf tawsf awtsf watsf twasf wtasf safwt asfwt sfawt fsawt afswt faswt sawft aswft swaft wsaft awsft wasft sfwat fswat swfat wsfat fwsat wfsat afwst fawst awfst wafst fwast wfast stfwa tsfwa sftwa fstwa tfswa ftswa stwfa tswfa swtfa wstfa twsfa wtsfa sfwta fswta swfta wsfta fwsta wfsta tfwsa ftwsa twfsa wtfsa fwtsa wftsa atfws tafws aftws fatws tfaws ftaws atwfs tawfs awtfs watfs twafs wtafs afwts fawts awfts wafts fwats wfats tfwas ftwas twfas wtfas fwtas wftas
Note: these 'words' (valid or invalid) are all the permutations of the word satfw. These words are obtained by scrambling the letters in satfw.