-er a-a a-b aaa aab aae aaf aan aao aap aar aax ab- aba abb abe abf abn abo abp abr abx aea aeb aee aef aen aeo aep aer aex af- afa afb afe aff afn afo afp afr afx an- ana anb ane anf ann ano anp anr anx aoa aob aoe aof aon aoo aop aor aox ap- apa apb ape apf apn apo app apr apx ar- ara arb are arf arn aro arp arr arx ax- axa axe axn axo axp axr axx b-p baa bab bae baf ban bao bap bar bax bba bbb bbe bbf bbn bbo bbp bbr bbx be- bea beb bee bef ben beo bep ber bex bfa bfb bfe bff bfn bfo bfp bfr bfx bna bnb bne bnf bnn bno bnp bnr bnx boa bob boe bof bon boo bop bor box bpa bpb bpe bpf bpn bpo bpp bpr bpx bra brb bre brf brn bro brp brr brx bxb bxn bxo bxx eaa eab eae eaf ean eao eap ear eax eba ebb ebe ebf ebn ebo ebp ebr ebx eea eeb eee eef een eeo eep eer eex ef- efa efb efe eff efo efp efr efx en- ena enb ene enf enn eno enp enr eo- eoa eob eoe eof eon eoo eop eor ep- epa epb epe epf epn epo epp epr epx era erb ere erf ern ero erp err ex- exa exe exo exp exr exx faa fab fae faf fan fao fap far fax fba fbb fbe fbf fbn fbo fbp fbr fbx fea feb fee fef fen feo fep fer fex ffa ffe fff ffn ffo ffp ffr ffx fna fnb fne fnf fnn fnp fnr fnx foa fob foe fof fon foo fop for fox fpa fpb fpe fpn fpo fpp fpr fpx fra frb fre frf frn fro frp frr fxe fxp fxr fxx naa nab nae naf nan nao nap nar nax nba nbb nbe nbf nbn nbo nbp nbr nbx ne- nea neb nee nef nen neo nep ner nex nfa nfb nfe nff nfn nfo nfp nfr nna nnb nne nnf nnn nno nnp no- noa nob noe nof non noo nop nor nox npa npb npe npf npn npo npp npr nra nrb nre nrf nrn nro nrp nrr nrx oaa oab oae oaf oan oao oap oar oax ob- oba obb obe obf obn obo obp obr obx oea oeb oee oef oen oeo oep oer oex of- ofa ofb ofe off ofn ofo ofp ofr ofx on- ona onb one onf onn ono onp onr onx oo- ooa oob oof oon ooo oop oor oox op- opa opb ope opf opn opo opp opr opx or- ora orb ore orf orn oro orp orr orx ox- oxa oxb oxf oxn oxo oxx p-p paa pab pae paf pan pao pap par pax pba pbb pbe pbf pbn pbo pbp pbr pbx pea peb pee pef pen peo pep per pex pfa pfb pfe pff pfn pfo pfp pfr pfx pn- pna pnb pne pnf pnn pno pnp pnr pnx poa pob poe pof pon poo pop por pox ppa ppb ppe ppf ppn ppo ppp ppr ppx pra prb pre prf prn pro prp prr prx pxe pxr ra- raa rab rae raf ran rao rap rar rax rba rbb rbe rbf rbn rbo rbp rbr rbx re- rea reb ree ref ren reo rep rer rex rfa rfb rfe rff rfn rfo rfp rfr rna rnb rnn rno rnp rnr roa rob roe rof ron roo rop ror rox rpa rpb rpe rpf rpn rpo rpp rpr rpx rra rrb rrf rrn rrp rrr rxp rxr xaa xaf xan xap xar xbe xbr xbx xee xen xep xer xex xfa xfe xfn xfx xna xno xoa xof xon xoo xop xor xox xpa xpb xpe xpf xpn xpo xpp xrf xrx xxo xxp xxx