a-a a-z aaa aao aap aar aas aax aaz aoa aoo aop aor aos aox ap- apa apo app apr aps apx ar- ara aro arp arr ars arx arz as- asa aso asp asr ass asx asz ax- axa axo axp axr axs axx az- aza azo azp azs azx azz oaa oao oap oar oas oax oo- ooa ooo oop oor oos oox op- opa opo opp opr ops opx or- ora oro orp orr ors orx orz os- osa oso osp osr oss osx ox- oxa oxo oxx oza ozo ozs ozz p-p paa pao pap par pas pax paz poa poo pop por pos pox poz ppa ppo ppp ppr pps ppx ppz pra pro prp prr prs prx prz ps- psa pso psp psr pss psx pxr pxs pzp ra- raa rao rap rar ras rax raz roa roo rop ror ros rox roz rpa rpo rpp rpr rps rpx rpz rra rrp rrr rrs rsa rso rsp rsr rss rsx rxp rxr rxs rza rzo saa sao sap sar sas sax saz soa soo sop sor sos sox soz spa spo spp spr sps spx spz sr- sra sro srp srr srs srx ss- ssa sso ssp ssr sss ssx ssz sxs sza szp szr xaa xap xar xas xoa xoo xop xor xos xox xpa xpo xpp xps xrx xsa xsp xss xxo xxp xxx zaa zao zap zar zas zax zaz zo- zoa zoo zor zos zox zpo zpp zpr zro zrp zrs zsa zsz zxx zzr zzs zzx zzz