-er a-a a-c aaa aac aae aak aao aap aar aas ac- aca acc ace ack aco acp acr acs aea aec aee aek aeo aep aer aes aka akc ake akk ako akp akr aks aoa aoc aoe aok aoo aop aor aos ap- apa apc ape apk apo app apr aps ar- ara arc are ark aro arp arr ars as- asa asc ase ask aso asp asr ass c-- caa cac cae cak cao cap car cas cca ccc cce cck cco ccp ccr ccs ce- cea cec cee cek ceo cep cer ces cka ckc cko cks co- coa coc coe cok coo cop cor cos cpa cpc cpe cpk cpo cpp cpr cps cra crc cre crk cro crp crr crs csa csc cse csk cso csp csr css eaa eac eae eak eao eap ear eas ec- eca ecc ece eck eco ecr ecs eea eec eee eek eeo eep eer ees eka ekc eke eko ekp ekr eks eo- eoa eoc eoe eok eoo eop eor eos ep- epa epc epe epo epp epr eps era erc ere erk ero erp err ers es- esa esc ese esk eso esp esr ess ka- kaa kac kae kak kao kap kar kas kca kcc kce kck kcp kcr kcs ke- kea kec kee kek keo kep ker kes kkc kke kkk kkp kkr kks koa koc koe kok koo kop kor kos kpa kpc kpe kpk kpo kpp kpr kps kra krc krk kro krp krr krs ksa ksc kse ksk kso ksp ksr kss oaa oac oae oak oao oap oar oas oc- oca occ ock oco ocp ocr ocs oea oec oee oeo oep oer oes oka okc oke okk oko okp okr oks oo- ooa ooc ook ooo oop oor oos op- opa opc ope opk opo opp opr ops or- ora orc ore ork oro orp orr ors os- osa osc ose osk oso osp osr oss p-p paa pac pae pak pao pap par pas pca pcc pce pck pco pcp pcr pcs pea pec pee pek peo pep per pes pka pkc pke pko pkp pkr pks poa poc poe pok poo pop por pos ppa ppc ppe ppk ppo ppp ppr pps pra prc pre prk pro prp prr prs ps- psa psc pse psk pso psp psr pss ra- raa rac rae rak rao rap rar ras rca rcc rce rco rcp rcr rcs re- rea rec ree rek reo rep rer res rkc rke rkk rko rkp rks roa roc roe rok roo rop ror ros rpa rpc rpe rpk rpo rpp rpr rps rra rrc rrk rrp rrr rrs rsa rsc rse rsk rso rsp rsr rss saa sac sae sak sao sap sar sas sca scc sce sck sco scp scr scs se- sea sec see sek seo sep ser ses sk- ska skc ske skk sko skp skr sks soa soc soe sok soo sop sor sos spa spc spe spk spo spp spr sps sr- sra src sre srk sro srp srr srs ss- ssa ssc sse ssk sso ssp ssr sss