bbbb bbeb bbet bbrc bcbc bccc bcec bcer bcet bctc bebb bebe beeb beer beet berc bere berr bert betc bete bett brcb brce breb brec bree brer bret brrr brtc btcc btec btrc btrt bttb cbbc cbcc cbce cbcr cbct cbec cbee cber cbet cbre cbrt cbtc ccbc cccb cccc ccee ccrc ccre ccrt cctb cctc cctt cec- cece cect ceeb ceec cer- cerc cere cert cet- cete crbc crcc crce crcr cre- creb crec cree cret crrt crtc ctec ctrc ebbc ebbr ebcc eber ecbc ecbe eccb eccc ecce ecct ecrc ecrr ect- ectc eeee eerc eetc eete erbb erbe ercc erce ereb erec erer eret errc erre etbc etbr etcc etec etee eter etre ette rbbb rbbr rcbc rccb rccc rcet rctc rebb rebe recc rece recr rect reeb reet rere rert rete retr rett rrrr rtcc rtce rtee tbcb tbcc tbce tbrb tccc tctc tecr tect teec teer teet ter- terc tere terr tete tetr tett trcc tre- trec tree tret trtc trte trtr ttbb tter tttt