-er a-a a-b a-c aaa aab aac aad aae aak aao aap aar aas ab- aba abb abc abd abe abk abo abp abr abs ac- aca acb acc acd ace ack aco acp acr acs ad- ada adb adc add ade adk ado adp adr ads aea aeb aec aed aee aek aeo aep aer aes aka akb akc akd ake akk ako akp akr aks aoa aob aoc aod aoe aok aoo aop aor aos ap- apa apb apc apd ape apk apo app apr aps ar- ara arb arc ard are ark aro arp arr ars as- asa asb asc asd ase ask aso asp asr ass b-p baa bab bac bad bae bak bao bap bar bas bba bbb bbc bbd bbe bbk bbo bbp bbr bbs bca bcb bcc bcd bce bck bco bcp bcr bcs bda bdb bdc bdd bde bdk bdo bdp bdr bds be- bea beb bec bed bee bek beo bep ber bes bka bkb bkc bke bkk bko bkp bkr bks boa bob boc bod boe bok boo bop bor bos bpa bpb bpc bpd bpe bpo bpp bpr bps bra brb brd bre brk bro brp brr brs bsa bsb bsc bsd bse bsk bso bsp bsr bss c-- caa cab cac cad cae cak cao cap car cas cba cbb cbc cbd cbe cbk cbo cbp cbr cbs cca ccb ccc ccd cce cck cco ccp ccr ccs cda cdb cdc cdd cde cdk cdo cdp cdr cds ce- cea ceb cec ced cee cek ceo cep cer ces cka ckb ckc ckd cko cks co- coa cob coc cod coe cok coo cop cor cos cpa cpb cpc cpd cpe cpk cpo cpp cpr cps cra crb crc crd cre crk cro crp crr crs csa csb csc csd cse csk cso csp csr css daa dab dac dad dae dak dao dap dar das dba dbb dbc dbd dbe dbk dbo dbp dbr dbs dca dcb dcc dcd dce dck dco dcp dcr dcs dda ddb ddc ddd dde ddk ddo ddp ddr dds de- dea deb dec ded dee dek deo dep der des dka dkb dkc dke dkk dko dkp dkr dks doa dob doc dod doe dok doo dop dor dos dpa dpb dpc dpd dpe dpk dpo dpp dpr dps dra drb drc drd dre drk dro drp drr drs dsa dsb dsc dsd dse dsk dso dsp dsr dss eaa eab eac ead eae eak eao eap ear eas eba ebb ebc ebd ebe ebk ebo ebp ebr ebs ec- eca ecb ecc ecd ece eck eco ecr ecs ed- eda edb edc edd ede edk edo edp edr eds eea eeb eec eed eee eek eeo eep eer ees eka ekb ekc ekd eke eko ekp ekr eks eo- eoa eob eoc eod eoe eok eoo eop eor eos ep- epa epb epc epd epe epo epp epr eps era erb erc erd ere erk ero erp err ers es- esa esb esc esd ese esk eso esp esr ess ka- kaa kab kac kad kae kak kao kap kar kas kba kbb kbc kbd kbe kbk kbo kbp kbr kbs kca kcb kcc kcd kce kck kcp kcr kcs kda kdb kdc kde kdk kdo kdp kdr kds ke- kea keb kec ked kee kek keo kep ker kes kkb kkc kke kkk kkp kkr kks koa kob koc kod koe kok koo kop kor kos kpa kpc kpd kpe kpk kpo kpp kpr kps kra krc krd krk kro krp krr krs ksa ksb ksc ksd kse ksk kso ksp ksr kss oaa oab oac oad oae oak oao oap oar oas ob- oba obb obc obd obe obk obo obp obr obs oc- oca ocb occ ocd ock oco ocp ocr ocs oda odb odc odd ode odo odp odr ods oea oeb oec oed oee oeo oep oer oes oka okb okc okd oke okk oko okp okr oks oo- ooa oob ooc ood ook ooo oop oor oos op- opa opb opc opd ope opk opo opp opr ops or- ora orb orc ord ore ork oro orp orr ors os- osa osb osc osd ose osk oso osp osr oss p-p paa pab pac pad pae pak pao pap par pas pba pbb pbc pbd pbe pbk pbo pbp pbr pbs pca pcb pcc pcd pce pck pco pcp pcr pcs pda pdb pdc pdd pde pdk pdo pdp pdr pds pea peb pec ped pee pek peo pep per pes pka pkb pkc pkd pke pko pkp pkr pks poa pob poc pod poe pok poo pop por pos ppa ppb ppc ppd ppe ppk ppo ppp ppr pps pra prb prc prd pre prk pro prp prr prs ps- psa psb psc psd pse psk pso psp psr pss ra- raa rab rac rad rae rak rao rap rar ras rba rbb rbc rbd rbe rbk rbo rbp rbr rbs rca rcb rcc rcd rce rco rcp rcr rcs rda rdb rdc rdd rde rdo rdp rdr rds re- rea reb rec red ree rek reo rep rer res rkb rkc rke rkk rko rkp rks roa rob roc rod roe rok roo rop ror ros rpa rpb rpc rpd rpe rpk rpo rpp rpr rps rra rrb rrc rrd rrk rrp rrr rrs rsa rsb rsc rsd rse rsk rso rsp rsr rss saa sab sac sad sae sak sao sap sar sas sba sbb sbc sbd sbe sbk sbo sbp sbr sbs sca scb scc scd sce sck sco scp scr scs sda sdb sdc sdd sde sdk sdo sdp sdr sds se- sea seb sec sed see sek seo sep ser ses sk- ska skb skc skd ske skk sko skp skr sks soa sob soc sod soe sok soo sop sor sos spa spb spc spd spe spk spo spp spr sps sr- sra srb src srd sre srk sro srp srr srs ss- ssa ssb ssc ssd