bbbb bbeb bbet bbrc bcbc bccc bcec bcer bcet bcor bctc bebb bebe bebo beeb beer beet beo- beor beot berc bere bero berr bert betc bete beto bett bobb bobe bobo boce boco boec boee boeo boer boet boob booc booe boor boot bor- bore boro borr bort botb bote boto bott brcb brce breb brec bree breo brer bret brob broc broe broo bror brot brrr brtc btcc btec btob btor btrc btrt bttb c-bo cbbc cbcc cbce cbcr cbct cbec cbee cber cbet cbot cbre cbrt cbtc ccbc cccb cccc ccee ccob ccoc ccrc ccre ccrt cctb cctc cctt cec- cece ceco cect ceeb ceec ceor cer- cerc cere cero cert cet- cete ceto cobb cobe cobo coce coco coct coob coot cor- corb corc core coro corr cort cotb cotc cote coto cott crbc crcc crce crcr cre- creb crec cree creo cret crob croc croe croo cror crot crrt crtc ctec ctor ctot ctrc ebbc ebbo ebbr ebcc eber eboe eboo ebor ebro ecbc ecbe eccb eccc ecce ecco ecct eco- ecot ecrc ecrr ect- ectc ecto eeee eeoc eerc eero eetc eete eore eotc eoto erbb erbe ercc erce ereb erec erer eret erob eroc eroe eroo errc erre erro etbc etbr etcc etco etec etee eter etoe etre etro ette etto o-eo obbo obec ober obet oboe obor obot obre obro ocbc occc occt oce ocee ocet ocre ocro ocrr oct- octe octo oec- oecc oeec oere oobe oocr ooer oooo oore oort ootb orbb orbe orbo orce orco ore- oreb orec oreo orer oro- oroe oror orot orro ortc orte orto otee oter oto- otoe otoo otor otre otro otte otto rbbb rbbr rcbc rcbo rccb rccc rcet rctc rebb rebe rebo recc rece recr rect reeb reet reot rere rero rert rete reto retr rett rob- robb robe robo robt rocc roce roco roer roet roob roor root rorc rore roro rort rotc rote roto rotr rott rrrr rtcc rtce rtee tbcb tbcc tbce tbrb tccc tctc tebo teco tecr tect teec teer teet teor ter- terc tere tero terr tete teto tetr tett tobe tobo tobt toce toco toee toer toet toor toot torc tore toro torr tort totc tote toto totr tott trcc tre- trec tree treo tret troc troe troo trot trtc trte trtr ttbb tteo tter ttoe tttt