-er a-a aaa aae aao aap aar aax aea aee aeo aep aer aex aoa aoe aoo aop aor aox ap- apa ape apo app apr apx ar- ara are aro arp arr arx ax- axa axe axo axp axr axx eaa eae eao eap ear eax eea eee eeo eep eer eex eo- eoa eoe eoo eop eor ep- epa epe epo epp epr epx era ere ero erp err ex- exa exe exo exp exr exx oaa oae oao oap oar oax oea oee oeo oep oer oex oo- ooa ooo oop oor oox op- opa ope opo opp opr opx or- ora ore oro orp orr orx ox- oxa oxo oxx p-p paa pae pao pap par pax pea pee peo pep per pex poa poe poo pop por pox ppa ppe ppo ppp ppr ppx pra pre pro prp prr prx pxe pxr ra- raa rae rao rap rar rax re- rea ree reo rep rer rex roa roe roo rop ror rox rpa rpe rpo rpp rpr rpx rra rrp rrr rxp rxr xaa xap xar xee xep xer xex xoa xoo xop xor xox xpa xpe xpo xpp xrx xxo xxp xxx