-er a-a a-c aaa aac aae aao aap aar ac- aca acc ace aco acp acr aea aec aee aeo aep aer aoa aoc aoe aoo aop aor ap- apa apc ape apo app apr ar- ara arc are aro arp arr c-- caa cac cae cao cap car cca ccc cce cco ccp ccr ce- cea cec cee ceo cep cer co- coa coc coe coo cop cor cpa cpc cpe cpo cpp cpr cra crc cre cro crp crr eaa eac eae eao eap ear ec- eca ecc ece eco ecr eea eec eee eeo eep eer eo- eoa eoc eoe eoo eop eor ep- epa epc epe epo epp epr era erc ere ero erp err oaa oac oae oao oap oar oc- oca occ oco ocp ocr oea oec oee oeo oep oer oo- ooa ooc ooo oop oor op- opa opc ope opo opp opr or- ora orc ore oro orp orr p-p paa pac pae pao pap par pca pcc pce pco pcp pcr pea pec pee peo pep per poa poc poe poo pop por ppa ppc ppe ppo ppp ppr pra prc pre pro prp prr ra- raa rac rae rao rap rar rca rcc rce rco rcp rcr re- rea rec ree reo rep rer roa roc roe roo rop ror rpa rpc rpe rpo rpp rpr rra rrc rrp rrr