bbbb bbbs bibb bibi bibs biis birb biri birr birs biru biry bis- biss bisu bisy biys bris brrr brrs brsb brsr brus bry- bubb bubi bubs bubu buir buis buiu bur- burb buri burr burs buru bury busi buss busu busy buus buyi buys buyu bysb bysi byss bysy i-by ibis ibri ibss ibus ibuy ibyi iiii iiis iirs iisi iisr iisu irby iri- iris iriy irri irrs irus isis isri issi issr isss issu issy isus isys iuiu iuss rbbb rbbr rbbs rbis rbss rib- ribs ribu riby riis riri rirs risi riss risu rius rrrr rsbi rsis rubb rubi rubs rubu ruby ruis ruri rurs ruru rusi russ rusu rusy ruyi ruys ryis rysy s-ib s-ii sbbs sbsi sbus sibi sibs sibu siby siri sirr sirs siru sisi siss sisu sisy siui sius siyi siyu srby srib sris srub ssbr ssby ssis ssri ssrs sssb sssi ssss sub- subb subi subs suir suis sur- suri surr surs suru sury sus- susi suss susu susy suus suyi suyr suyu syis syrs syry syss ubbi ubii ubir ubis uirr urbi urbs urib uris uriu urri urry ursi urss ursu ursy urur urus usbr usbs usis ussb ussr usss ussu ussy usui usus uuri uusi uuuu uyir ybbs ybry yirb yirr yiss ysby ysii yssu ysyb yubu yuri yury yuyu yyyy