a-a a-b a-c aaa aab aac aad aak aan aao aar aas ab- aba abb abc abd abk abn abo abr abs ac- aca acb acc acd ack acn aco acr acs ad- ada adb adc add adk adn ado adr ads aka akb akc akd akk akn ako akr aks an- ana anb anc and ank ann ano anr ans aoa aob aoc aod aok aon aoo aor aos ar- ara arb arc ard ark arn aro arr ars as- asa asb asc asd ask asn aso asr ass baa bab bac bad bak ban bao bar bas bba bbb bbc bbd bbk bbn bbo bbr bbs bca bcb bcc bcd bck bcn bco bcr bcs bda bdb bdc bdd bdk bdo bdr bds bka bkb bkc bkk bkn bko bkr bks bna bnb bnc bnd bnk bnn bno bnr bns boa bob boc bod bok bon boo bor bos bra brb brd brk brn bro brr brs bsa bsb bsc bsd bsk bsn bso bsr bss c-- caa cab cac cad cak can cao car cas cba cbb cbc cbd cbk cbn cbo cbr cbs cca ccb ccc ccd cck ccn cco ccr ccs cda cdb cdc cdd cdk cdn cdo cdr cds cka ckb ckc ckd cko cks cn- cna cnb cnc cnd cnn cno cnr cns co- coa cob coc cod cok con coo cor cos cra crb crc crd crk crn cro crr crs csa csb csc csd csk csn cso csr css daa dab dac dad dak dan dao dar das dba dbb dbc dbd dbk dbn dbo dbr dbs dca dcb dcc dcd dck dcn dco dcr dcs dda ddb ddc ddd ddk ddn ddo ddr dds dka dkb dkc dkk dko dkr dks dna dnb dnc dnd dnk dnn dno dnr dns doa dob doc dod dok don doo dor dos dra drb drc drd drk drn dro drr drs dsa dsb dsc dsd dsk dsn dso dsr dss ka- kaa kab kac kad kak kan kao kar kas kba kbb kbc kbd kbk kbn kbo kbr kbs kca kcb kcc kcd kck kcn kcr kcs kda kdb kdc kdk kdo kdr kds kkb kkc kkk kkn kkr kks kn- kna knc knd knk knn kno knr koa kob koc kod kok kon koo kor kos kra krc krd krk krn kro krr krs ksa ksb ksc ksd ksk ksn kso ksr kss naa nab nac nad nak nan nao nar nas nba nbb nbc nbd nbk nbn nbo nbr nbs nca ncb ncc ncd nck ncn nco ncr ncs nda ndb ndc ndd ndk ndn ndo ndr nds nka nkc nkk nkn nko nkr nks nna nnb nnc nnk nnn nno nns no- noa nob noc nod nok non noo nor nos nra nrb nrc nrd nrk nrn nro nrr nrs nsa nsb nsc nsd nsk nsn nso nsr nss oaa oab oac oad oak oan oao oar oas ob- oba obb obc obd obk obn obo obr obs oc- oca ocb occ ocd ock ocn oco ocr ocs oda odb odc odd odn odo odr ods oka okb okc okd okk oko okr oks on- ona onb onc ond onk onn ono onr ons oo- ooa oob ooc ood ook oon ooo oor oos or- ora orb orc ord ork orn oro orr ors os- osa osb osc osd osk osn oso osr oss ra- raa rab rac rad rak ran rao rar ras rba rbb rbc rbd rbk rbn rbo rbr rbs rca rcb rcc rcd rcn rco rcr rcs rda rdb rdc rdd rdn rdo rdr rds rkb rkc rkk rko rks rna rnb rnc rnd rnn rno rnr rns roa rob roc rod rok ron roo ror ros rra rrb rrc rrd rrk rrn rrr rrs rsa rsb rsc rsd rsk rsn rso rsr rss saa sab sac sad sak san sao sar sas sba sbb sbc sbd sbk sbn sbo sbr sbs sca scb scc scd sck scn sco scr scs sda sdb sdc sdd sdk sdn sdo sdr sds sk- ska skb skc skd skk sko skr sks sna snb snc snd snk snn sno snr sns soa sob soc sod sok son soo sor sos sr- sra srb src srd srk srn sro srr srs ss- ssa ssb ssc ssd ssk ssn sso ssr sss