-er c-- ccc cce cck cco ccp ccr ccs ce- cec cee cek ceo cep cer ces ckc cko cks co- coc coe cok coo cop cor cos cpc cpe cpk cpo cpp cpr cps crc cre crk cro crp crr crs csc cse csk cso csp csr css ec- ecc ece eck eco ecr ecs eec eee eek eeo eep eer ees ekc eke eko ekp ekr eks eo- eoc eoe eok eoo eop eor eos ep- epc epe epo epp epr eps erc ere erk ero erp err ers es- esc ese esk eso esp esr ess kcc kce kck kcp kcr kcs ke- kec kee kek keo kep ker kes kkc kke kkk kkp kkr kks koc koe kok koo kop kor kos kpc kpe kpk kpo kpp kpr kps krc krk kro krp krr krs ksc kse ksk kso ksp ksr kss oc- occ ock oco ocp ocr ocs oec oee oeo oep oer oes okc oke okk oko okp okr oks oo- ooc ook ooo oop oor oos op- opc ope opk opo opp opr ops or- orc ore ork oro orp orr ors os- osc ose osk oso osp osr oss p-p pcc pce pck pco pcp pcr pcs pec pee pek peo pep per pes pkc pke pko pkp pkr pks poc poe pok poo pop por pos ppc ppe ppk ppo ppp ppr pps prc pre prk pro prp prr prs ps- psc pse psk pso psp psr pss rcc rce rco rcp rcr rcs re- rec ree rek reo rep rer res rkc rke rkk rko rkp rks roc roe rok roo rop ror ros rpc rpe rpk rpo rpp rpr rps rrc rrk rrp rrr rrs rsc rse rsk rso rsp rsr rss scc sce sck sco scp scr scs se- sec see sek seo sep ser ses sk- skc ske skk sko skp skr sks soc soe sok soo sop sor sos spc spe spk spo spp spr sps sr- src sre srk sro srp srr srs ss- ssc sse ssk sso ssp ssr sss