-er a-a a-b aaa aab aae aan aao aap aar aas ab- aba abb abe abn abo abp abr abs aea aeb aee aen aeo aep aer aes an- ana anb ane ann ano anp anr ans aoa aob aoe aon aoo aop aor aos ap- apa apb ape apn apo app apr aps ar- ara arb are arn aro arp arr ars as- asa asb ase asn aso asp asr ass b-p baa bab bae ban bao bap bar bas bba bbb bbe bbn bbo bbp bbr bbs be- bea beb bee ben beo bep ber bes bna bnb bne bnn bno bnp bnr bns boa bob boe bon boo bop bor bos bpa bpb bpe bpn bpo bpp bpr bps bra brb bre brn bro brp brr brs bsa bsb bse bsn bso bsp bsr bss eaa eab eae ean eao eap ear eas eba ebb ebe ebn ebo ebp ebr ebs eea eeb eee een eeo eep eer ees en- ena enb ene enn eno enp enr ens eo- eoa eob eoe eon eoo eop eor eos ep- epa epb epe epn epo epp epr eps era erb ere ern ero erp err ers es- esa esb ese esn eso esp esr ess naa nab nae nan nao nap nar nas nba nbb nbe nbn nbo nbp nbr nbs ne- nea neb nee nen neo nep ner nes nna nnb nne nnn nno nnp nns no- noa nob noe non noo nop nor nos npa npb npe npn npo npp npr nps nra nrb nre nrn nro nrp nrr nrs nsa nsb nse nsn nso nsp nsr nss oaa oab oae oan oao oap oar oas ob- oba obb obe obn obo obp obr obs oea oeb oee oen oeo oep oer oes on- ona onb one onn ono onp onr ons oo- ooa oob oon ooo oop oor oos op- opa opb ope opn opo opp opr ops or- ora orb ore orn oro orp orr ors os- osa osb ose osn oso osp osr oss p-p paa pab pae pan pao pap par pas pba pbb pbe pbn pbo pbp pbr pbs pea peb pee pen peo pep per pes pn- pna pnb pne pnn pno pnp pnr pns poa pob poe pon poo pop por pos ppa ppb ppe ppn ppo ppp ppr pps pra prb pre prn pro prp prr prs ps- psa psb pse psn pso psp psr pss ra- raa rab rae ran rao rap rar ras rba rbb rbe rbn rbo rbp rbr rbs re- rea reb ree ren reo rep rer res rna rnb rnn rno rnp rnr rns roa rob roe ron roo rop ror ros rpa rpb rpe rpn rpo rpp rpr rps rra rrb rrn rrp rrr rrs rsa rsb rse rsn rso rsp rsr rss saa sab sae san sao sap sar sas sba sbb sbe sbn sbo sbp sbr sbs se- sea seb see sen seo sep ser ses sna snb sne snn sno snp snr sns soa sob soe son soo sop sor sos spa spb spe spn spo spp spr sps sr- sra srb sre srn sro srp srr srs ss- ssa ssb sse ssn sso ssp ssr sss