-er c-- ccc cce cck cco ccp ccr cct ce- cec cee cek ceo cep cer cet ckc cko ckt co- coc coe cok coo cop cor cot cpc cpe cpk cpo cpp cpr cpt crc cre crk cro crp crr crt ctc cte ctk cto ctp ctr ctt ec- ecc ece eck eco ecr ect eec eee eek eeo eep eer eet ekc eke eko ekp ekr ekt eo- eoc eoe eok eoo eop eor eot ep- epc epe epo epp epr ept erc ere erk ero erp err ert etc ete etk eto etp etr ett k-t kcc kce kck kcp kcr kct ke- kec kee kek keo kep ker ket kkc kke kkk kkp kkr kkt koc koe kok koo kop kor kot kpc kpe kpk kpo kpp kpr kpt krc krk kro krp krr krt ktc kte ktk kto ktp ktr ktt oc- occ ock oco ocp ocr oct oec oee oeo oep oer oet okc oke okk oko okp okr oo- ooc ook ooo oop oor oot op- opc ope opk opo opp opr opt or- orc ore ork oro orp orr ort ot- otc ote otk oto otp otr ott p-p pcc pce pck pco pcp pcr pct pec pee pek peo pep per pet pkc pke pko pkp pkr pkt poc poe pok poo pop por pot ppc ppe ppk ppo ppp ppr ppt prc pre prk pro prp prr prt pt- ptc pte ptk pto ptp ptr ptt rcc rce rco rcp rcr rct re- rec ree rek reo rep rer ret rkc rke rkk rko rkp rkt roc roe rok roo rop ror rot rpc rpe rpk rpo rpp rpr rpt rrc rrk rrp rrr rrt rtc rte rtk rto rtp rtr rtt tcc tce tck tco tcp tcr tct te- tec tee tek teo tep ter tet tkc tke tkk tko tkp tkr tkt to- toc toe tok too top tor tot tpc tpe tpk tpo tpp tpr tpt trc tre trk tro trp trr trt ttc tte ttk tto ttp ttr ttt