riffs irffs rfifs frifs ifrfs firfs riffs irffs rfifs frifs ifrfs firfs rffis frfis rffis frfis ffris ffris iffrs fifrs iffrs fifrs ffirs ffirs rifsf irfsf rfisf frisf ifrsf firsf risff irsff rsiff sriff isrff sirff rfsif frsif rsfif srfif fsrif sfrif ifsrf fisrf isfrf sifrf fsirf sfirf rifsf irfsf rfisf frisf ifrsf firsf risff irsff rsiff sriff isrff sirff rfsif frsif rsfif srfif fsrif sfrif ifsrf fisrf isfrf sifrf fsirf sfirf rffsi frfsi rffsi frfsi ffrsi ffrsi rfsfi frsfi rsffi srffi fsrfi sfrfi rfsfi frsfi rsffi srffi fsrfi sfrfi ffsri ffsri fsfri sffri fsfri sffri iffsr fifsr iffsr fifsr ffisr ffisr ifsfr fisfr isffr siffr fsifr sfifr ifsfr fisfr isffr siffr fsifr sfifr ffsir ffsir fsfir sffir fsfir sffir
Note: these 'words' (valid or invalid) are all the permutations of the word riffs. These words are obtained by scrambling the letters in riffs.