bbbb bbwr bobb bobo bobu bobw boob boor boot boow bor- boro borr bort boru borw botb boto bott botw bour bout bouw bowr bowt brob broo bror brot brou brow brrr brut btob btor btrt bttb btwo bubb bubo bubu bur- burb buro burr burt buru but- buto butt obbo obor obot obro oooo oort ootb ootw orbb orbo orbu oro- oror orot orro orto orub orwo oto- otoo otor otow otro otto ottu otur otwo our- ouro ourt out- outb outo ouu- owow owt- owtt owur rbbb rbbr rob- robb robo robt robu roob roor root roro rort roru roto rotr rott roub rout rowb rowr rowt roww rrrr rubb rubu ruro ruru ruto rutt rutu tbrb tobo tobt tobu toor toot toro torr tort toru toto totr tott tour tout troo trot trou trow trtr trub trut truu ttbb tttt tubb tubo tubr tubu tuor turb turo turr turt turu tuto tutt tutu tuuo twbt two- twob twoo twot ubbo uor- uro- uroo urur urut utor utto uttu utwo uuuu wbbb wbbo wbbr wbbt wbbw wbob wbor wbow wbrb wbrr wbrt wbru wbrw wbto wbtr wbtt wbtu wbtw wbut wbuw wbwb wbwo wbwt wobb wobo wobt woob woot woow worb woro worr wort worw wotb wotr wott wotw woub wour wout wouw wowb wowo wowt woww wrbb wrbo wrbt wrbu wrbw wrob wroo wrot wrow wrrb wrro wrrw wrtb wrto wrtr wrtu wrtw wrub wrwb wrwr wtbb wtbo wtbr wtbu wtob wtor wtot wtou wtow wtrb wtro wtrt wtru wtrw wttb wtto wttr wttt wttu wttw wtwb wtwo wtwr wtwt wtww wubb wubr wubt wubu wuot wur- wurb wurt wutb wutr wutu wuub wuuu wwbb wwbr wwbt wwbu wwor wwot wwow wwrb wwrr wwru wwrw wwtr wwtw wwwr wwww