bbbb bbbs bnrr bnss brns brrr brrs brsb brsr brst brun brus brut bsns bsts btrt btss bttb btus bubb bubs bubu bunb bunn buns bunt bunu bur- burb burn burr burs burt buru buss bust busu but- buts butt buus nnnn nnss nntn nrts nsnr nssb nssr nsss nsts nstu nsub ntnu ntru ntsb ntss ntsu nttr nubs nunn nuns nunt nurn nurr nurs nurt nuru nuss nust nusu nuts nutt nutu rbbb rbbr rbbs rbss rbst rnbr rnnt rnut rrrr rrun rsnn rsnr rsts rstu rtns rtss rtts rubb rubs rubu runn runs runt rurs ruru russ rust rusu ruts rutt rutu ruun sbbs sbst sbtn sbus snns snrs sntr snub snur snus srnn srtr srub ssbn ssbr ssns ssrs sssb ssss sstb ssts stbs stnn stnr stns strn strs stru stss sttr stub stun stur stus stut sub- subb subs sun- sunb sunn suns sunt sunu sur- surn surr surs surt suru sus- suss sust susu sutu suus tbbs tbrb tbst tnts tnut trst trtr trub trun trus trut truu tssr tsst tsts tsun ttbb ttss tttt tubb tubr tubs tubu tunb tunn tuns tunu turb turn turr turs turt turu tuss tust tuts tutt tutu unns unrs uns- unst untb unts unus unut urbs urns urss ursu urts urun urur urus urut usbr usbs usnr usnu ussb ussr usss usst ussu ustb usts usun usus uttu uuuu