bbbb bbbs bbhs bhhs bhut bhuu bshs bsts bths btss bttb btus bubb bubs bubu buhs bush buss bust busu but- buts butt buus hbbs hbhs hbss hbtu hhhh hhhs hhus hshs hsts hths hubb hubs huhs huhu hush huss hust huth huts hutt hutu huub huus sbbs sbhs sbst sbus shbs shbt shhh shhs shts shub shus shut shuu sshs sssb sssh ssss sstb ssth ssts stbs sths stss stub stus stut sub- subb subh subs suhb sus- suss sust susu sutu suus tbbs tbhs tbst thbs thss thtb thts thus tshb tshs tsst tsts ttbb ttss tttt tubb tubs tubu tuhs tuht tuhu tush tuss tust tuts tutt tutu uhss uhuh usbs ushs ushu ussb usss usst ussu ustb usts usus uttu uuuu