-er a-a a-c aaa aac aae aak aan aao aap aar ac- aca acc ace ack acn aco acp acr aea aec aee aek aen aeo aep aer aka akc ake akk akn ako akp akr an- ana anc ane ank ann ano anp anr aoa aoc aoe aok aon aoo aop aor ap- apa apc ape apk apn apo app apr ar- ara arc are ark arn aro arp arr c-- caa cac cae cak can cao cap car cca ccc cce cck ccn cco ccp ccr ce- cea cec cee cek cen ceo cep cer cka ckc cko cn- cna cnc cne cnn cno cnp cnr co- coa coc coe cok con coo cop cor cpa cpc cpe cpk cpn cpo cpp cpr cra crc cre crk crn cro crp crr eaa eac eae eak ean eao eap ear ec- eca ecc ece eck ecn eco ecr eea eec eee eek een eeo eep eer eka ekc eke eko ekp ekr en- ena enc ene enk enn eno enp enr eo- eoa eoc eoe eok eon eoo eop eor ep- epa epc epe epn epo epp epr era erc ere erk ern ero erp err ka- kaa kac kae kak kan kao kap kar kca kcc kce kck kcn kcp kcr ke- kea kec kee kek ken keo kep ker kkc kke kkk kkn kkp kkr kn- kna knc kne knk knn kno knp knr koa koc koe kok kon koo kop kor kpa kpc kpe kpk kpn kpo kpp kpr kra krc krk krn kro krp krr naa nac nae nak nan nao nap nar nca ncc nce nck ncn nco ncp ncr ne- nea nec nee nek nen neo nep ner nka nkc nke nkk nkn nko nkp nkr nna nnc nne nnk nnn nno nnp no- noa noc noe nok non noo nop nor npa npc npe npn npo npp npr nra nrc nre nrk nrn nro nrp nrr oaa oac oae oak oan oao oap oar oc- oca occ ock ocn oco ocp ocr oea oec oee oen oeo oep oer oka okc oke okk oko okp okr on- ona onc one onk onn ono onp onr oo- ooa ooc ook oon ooo oop oor op- opa opc ope opk opn opo opp opr or- ora orc ore ork orn oro orp orr p-p paa pac pae pak pan pao pap par pca pcc pce pck pcn pco pcp pcr pea pec pee pek pen peo pep per pka pkc pke pkn pko pkp pkr pn- pna pnc pne pnk pnn pno pnp pnr poa poc poe pok pon poo pop por ppa ppc ppe ppk ppn ppo ppp ppr pra prc pre prk prn pro prp prr ra- raa rac rae rak ran rao rap rar rca rcc rce rcn rco rcp rcr re- rea rec ree rek ren reo rep rer rkc rke rkk rko rkp rna rnc rnn rno rnp rnr roa roc roe rok ron roo rop ror rpa rpc rpe rpk rpn rpo rpp rpr rra rrc rrk rrn rrp rrr