rtfgh trfgh rftgh frtgh tfrgh ftrgh rtgfh trgfh rgtfh grtfh tgrfh gtrfh rfgth frgth rgfth grfth fgrth gfrth tfgrh ftgrh tgfrh gtfrh fgtrh gftrh rtfhg trfhg rfthg frthg tfrhg ftrhg rthfg trhfg rhtfg hrtfg thrfg htrfg rfhtg frhtg rhftg hrftg fhrtg hfrtg tfhrg fthrg thfrg htfrg fhtrg hftrg rtghf trghf rgthf grthf tgrhf gtrhf rthgf trhgf rhtgf hrtgf thrgf htrgf rghtf grhtf rhgtf hrgtf ghrtf hgrtf tghrf gthrf thgrf htgrf ghtrf hgtrf rfght frght rgfht grfht fgrht gfrht rfhgt frhgt rhfgt hrfgt fhrgt hfrgt rghft grhft rhgft hrgft ghrft hgrft fghrt gfhrt fhgrt hfgrt ghfrt hgfrt tfghr ftghr tgfhr gtfhr fgthr gfthr tfhgr fthgr thfgr htfgr fhtgr hftgr tghfr gthfr thgfr htgfr ghtfr hgtfr fghtr gfhtr fhgtr hfgtr ghftr hgftr
Note: these 'words' (valid or invalid) are all the permutations of the word rtfgh. These words are obtained by scrambling the letters in rtfgh.