bbbb bbbs bibb bibi bibs biis bis- biss bisu bisy biys bubb bubi bubs bubu buis buiu busi buss busu busy buus buyi buys buyu bysb bysi byss bysy i-by ibis ibss ibus ibuy ibyi iiii iiis iisi iisu isis issi isss issu issy isus isys iuiu iuss s-ib s-ii sbbs sbsi sbus sibi sibs sibu siby sisi siss sisu sisy siui sius siyi siyu ssby ssis sssb sssi ssss sub- subb subi subs suis sus- susi suss susu susy suus suyi suyu syis syss ubbi ubii ubis usbs usis ussb usss ussu ussy usui usus uusi uuuu ybbs yiss ysby ysii yssu ysyb yubu yuyu yyyy