ffff ffii ffrr ffss fiff fifi fiii firs fisi fiss fisu fris fsfi fssf fuff fufu fuir fur- furi furr furs fusi fuss fusu ifis ifrf ifri iiii iiis iirs iisi iisr iisu irfu iri- iris irri irrs irsf irus isis isri issf issi issr isss issu isus iuiu iuss riff rifs rifu riif riis riri rirs risi riss risu rius rrif rrrr rsis ruff ruif ruis ruri rurs ruru rusi russ rusu s-ii sfss sfsu siff sifr sifu sirf siri sirr sirs siru sisi siss sisu siui sius srfi sris ssis ssri ssrs sssf sssi ssss suf- suff sufi sufr sufs sufu suir suis sur- surf suri surr surs suru sus- susi suss susu suus uirr urff urfi urif uris uriu urri ursi urss ursu urur urus usfi usfs usif usis ussf ussr usss ussu usui usus uuri uusi uuuu