-er c-- ccc cce cck cco ccp ccr ccs ccx ce- cec cee cek ceo cep cer ces cex ckc cko cks ckx co- coc coe cok coo cop cor cos cox cpc cpe cpk cpo cpp cpr cps cpx crc cre crk cro crp crr crs crx csc cse csk cso csp csr css csx cxc cxk cxo cxp cxr cxs cxx ec- ecc ece eck eco ecr ecs ecx eec eee eek eeo eep eer ees eex ekc eke eko ekp ekr eks eo- eoc eoe eok eoo eop eor eos ep- epc epe epo epp epr eps epx erc ere erk ero erp err ers es- esc ese esk eso esp esr ess esx ex- exc exe exo exp exr exs exx kcc kce kck kcp kcr kcs kcx ke- kec kee kek keo kep ker kes kex 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 kxo oc- occ ock oco ocp ocr ocs ocx oec oee oeo oep oer oes oex okc oke okk oko okp okr oks oo- ooc ook ooo oop oor oos oox op- opc ope opk opo opp opr ops opx or- orc ore ork oro orp orr ors orx os- osc ose osk oso osp osr oss osx ox- oxc oxo oxx p-p pcc pce pck pco pcp pcr pcs pcx pec pee pek peo pep per pes pex pkc pke pko pkp pkr pks poc poe pok poo pop por pos pox ppc ppe ppk ppo ppp ppr pps ppx prc pre prk pro prp prr prs prx ps- psc pse psk pso psp psr pss psx pxc pxe pxk pxr pxs rcc rce rco rcp rcr rcs rcx re- rec ree rek reo rep rer res rex rkc rke rkk rko rkp rks roc roe rok roo rop ror ros rox rpc rpe rpk rpo rpp rpr rps rpx rrc rrk rrp rrr rrs rsc rse rsk rso rsp rsr rss rsx rxp rxr rxs scc sce sck sco scp scr scs scx se- sec see sek seo sep ser ses sex sk- skc ske skk sko skp skr sks skx soc soe sok soo sop sor sos sox spc spe spk spo spp spr sps spx sr- src sre srk sro srp srr srs srx ss- ssc sse ssk sso ssp ssr sss ssx sxc sxs xcp xcr xcx xee xep xer xes xex xke xks xoc xok xoo xop xor xos xox xpc xpe xpo xpp xps xrc xrx xsc xsp xss xxo xxp xxx