rfvi frvi rvfi vrfi fvri vfri rfiv friv rifv irfv firv ifrv rvif vrif rivf irvf virf ivrf fvir vfir fivr ifvr vifr ivfr
Note: these 'words' (valid or invalid) are all the permutations of the word rfvi. These words are obtained by scrambling the letters in rfvi.