bbbb bbbs bbrg bggs bgst brrr brrs brsb brsr brst brug brus brut bsgs bsts btrt btss bttb btus bubb bubs bubu bugg bugs bur- burb burg burr burs burt buru buss bust busu but- buts butt buus gbbs ggbt gggg ggss grbr grrr grrs grss grub grug grur grus grut gstr gsur gtbr gubb gubs gubu gugb gugg gugu gurb gurg gurr gurs gurt guru gusb guss gust guts gutt gutu guus rbbb rbbr rbbs rbss rbst rgtr rgts rrrr rsgb rsts rstu rtgs rtss rtts rubb rubs rubu rugg rugs rurs ruru russ rust rusu ruts rutt rutu sbbs sbst sbus sggg sggs sgss sgts srgb srtr srub ssbr ssgs ssgt ssrg ssrs sssb ssss sstb ssts stbs stgr strs stru stss sttr stub stug stur stus stut sub- subb subg subs sug- sugg sur- surg surr surs surt suru sus- suss sust susu sutu suus tbbs tbgs tbrb tbst tgts trst trtr trub trug trus trut truu tsgt tssg tssr tsst tsts ttbb ttss tttt tubb tubr tubs tubu tugg tugs tugu turb turg turr turs turt turu tuss tust tuts tutt tutu uggs uggt ugur uguu urbs urgu urss ursu urts urur urus urut usbr usbs ussb ussr usss usst ussu ustb usts usus uttu utug uuuu