bbbb bbbs bblb bbls bffl bffs bfts bftt blbt blls blss blst blts blub bluf blus blut bsff bsfs bsts btss bttb btus bubb bubs bubu buff bulb bull buls bult bulu buss bust busu but- buts butt buus fbus ffff ffss fftf flts flub fluf flus fssf ft-l ftlb ftub fubb fubs fubu fuff fufu full fuls fulu fuss fust fusu futs futu lfts llbs llll lsbu lsts ltbf ltbl lubs luff luft lufu lull lulu luss lust luts sbbs sbst sbus sfls sfss sfsu sfts slft slst slsu slts slub slut ssfl sslt sssb sssf ssss sstb sstl ssts stbs stfu stlt stsf stss stub stuf stul stus stut sub- subb subl subs suf- suff sufs sufu sul- sulf sull sult sulu sus- suss sust susu sutu suus tbbs tbst tfss tsfl tssf tsst tsts ttbb ttff ttss tttt ttul tubb tubs tubu tuff tuft tufu tull tulu tuss tust tutl tuts tutt tutu ubls ubtf ulft ults ultt ulul ulus usbl usbs usfl usfs uslu ussb ussf usss usst ussu ustb usts usul usus utsl uttu uulu uutf uuuu