-er a-a a-b a-c aaa aab aac aae aah aak aao aar aas ab- aba abb abc abe abh abk abo abr abs ac- aca acb acc ace ach ack aco acr acs aea aeb aec aee aeh aek aeo aer aes aha ahb ahc ahe ahh ahk aho ahr ahs aka akb akc ake akh akk ako akr aks aoa aob aoc aoe aoh aok aoo aor aos ar- ara arb arc are arh ark aro arr ars as- asa asb asc ase ash ask aso asr ass baa bab bac bae bah bak bao bar bas bba bbb bbc bbe bbh bbk bbo bbr bbs bca bcb bcc bce bch bck bco bcr bcs be- bea beb bec bee beh bek beo ber bes bha bhb bhc bhe bhh bhk bho bhr bhs bka bkb bkc bke bkk bko bkr bks boa bob boc boe boh bok boo bor bos bra brb bre brh brk bro brr brs bsa bsb bsc bse bsh bsk bso bsr bss c-- caa cab cac cae cah cak cao car cas cba cbb cbc cbe cbh cbk cbo cbr cbs cca ccb ccc cce cch cck cco ccr ccs ce- cea ceb cec cee ceh cek ceo cer ces ch- cha chb chc che chh chk cho chr chs cka ckb ckc ckh cko cks co- coa cob coc coe coh cok coo cor cos cra crb crc cre crh crk cro crr crs csa csb csc cse csh csk cso csr css eaa eab eac eae eah eak eao ear eas eba ebb ebc ebe ebh ebk ebo ebr ebs ec- eca ecb ecc ece ech eck eco ecr ecs eea eeb eec eee eek eeo eer ees eha ehb ehc ehe ehh eho ehr ehs eka ekb ekc eke ekh eko ekr eks eo- eoa eob eoc eoe eoh eok eoo eor eos era erb erc ere erh erk ero err ers es- esa esb esc ese esh esk eso esr ess haa hab hac hae hah hak hao har has hba hbb hbc hbe hbh hbk hbo hbr hbs hca hcb hcc hce hch hck hco hcr hcs he- hea heb hec hee heh hek heo her hes hha hhb hhc hhe hhh hhk hho hhr hhs hka hkb hkh hkk hko hkr hks hoa hob hoc hoe hoh hok hoo hor hos hr- hra hrb hrc hre hrh hrk hro hrr hrs hsa hsb hsc hse hsh hsk hsr hss ka- kaa kab kac kae kah kak kao kar kas kba kbb kbc kbe kbh kbk kbo kbr kbs kca kcb kcc kce kch kck kcr kcs ke- kea keb kec kee keh kek keo ker kes kha khe khh khk kho khr khs kkb kkc kke kkh kkk kkr kks koa kob koc koe koh kok koo kor kos kra krc krk kro krr krs ksa ksb ksc kse ksh ksk kso ksr kss oaa oab oac oae oah oak oao oar oas ob- oba obb obc obe obh obk obo obr obs oc- oca ocb occ och ock oco ocr ocs oea oeb oec oee oeh oeo oer oes oha ohc ohe ohh oho ohr ohs oka okb okc oke okk oko okr oks oo- ooa oob ooc ooh ook ooo oor oos or- ora orb orc ore orh ork oro orr ors os- osa osb osc ose osh osk oso osr oss ra- raa rab rac rae rah rak rao rar ras rba rbb rbc rbe rbh rbk rbo rbr rbs rca rcb rcc rce rch rco rcr rcs re- rea reb rec ree reh rek reo rer res rh- rha rhb rhc rhe rhh rho rhr rhs rkb rkc rke rkk rko rks roa rob roc roe roh rok roo ror ros rra rrb rrc rrh rrk rrr rrs rsa rsb rsc rse rsh rsk rso rsr rss saa sab sac sae sah sak sao sar sas sba sbb sbc sbe sbh sbk sbo sbr sbs sca scb scc sce sch sck sco scr scs se- sea seb sec see seh sek seo ser ses sh- sha shb shc she shh shk sho shr shs sk- ska skb skc ske skh skk sko skr sks soa sob soc soe soh sok soo sor sos sr- sra srb src sre srh srk sro srr srs ss- ssa ssb ssc sse ssh ssk sso ssr sss