bbbb bobb bobo boko boob book boor boot bor- bork boro borr bort botb boto bott brkb brob brok broo bror brot brrr btob btor btrt bttb kbbb kbbk kbbo kbbr kbbt kbkb kbkk kbko kbkr kbob kbok kboo kbot kbrb kbrk kbro kbrt kbtb kbtk kbto kbtr kbtt kkbb kkbo kkbr kkbt kkkk kkob kkoo kkor kkot kkrb kkrk kkro kkrr kkrt kktk kobb kobk kobo kobr kokb kokk koko kokr koob kook kooo koor koot korb kork koro korr kort kotb kotk koto kotr kott krbb krbk krbr krbt krkk krko krkr krob krok kroo kror krrb krrk krro krrr krrt krtk krto krtr ktbb ktbr ktbt ktkb ktkk ktko ktkr ktkt ktob ktok ktoo ktor ktot ktrb ktrk ktro ktrr ktrt kttk ktto kttr kttt obbo obkb obok obor obot obro okko okok okor okot okro okto oooo oort ootb orbb orbo orko oro- orok oror orot orro orto oto- otok otoo otor otro otto rbbb rbbr rob- robb robo robt rokk roko rokr roob rook roor root rork roro rort rotk roto rotr rott rrrr tbrb tobo tobt toko took toor toot tork toro torr tort toto totr tott troo trot trtr ttbb tttt