a-a a-b aaa aab aad aak aao aar aas ab- aba abb abd abk abo abr abs ad- ada adb add adk ado adr ads aka akb akd akk ako akr aks aoa aob aod aok aoo aor aos ar- ara arb ard ark aro arr ars as- asa asb asd ask aso asr ass baa bab bad bak bao bar bas bba bbb bbd bbk bbo bbr bbs bda bdb bdd bdk bdo bdr bds bka bkb bkk bko bkr bks boa bob bod bok boo bor bos bra brb brd brk bro brr brs bsa bsb bsd bsk bso bsr bss daa dab dad dak dao dar das dba dbb dbd dbk dbo dbr dbs dda ddb ddd ddk ddo ddr dds dka dkb dkk dko dkr dks doa dob dod dok doo dor dos dra drb drd drk dro drr drs dsa dsb dsd dsk dso dsr dss ka- kaa kab kad kak kao kar kas kba kbb kbd kbk kbo kbr kbs kda kdb kdk kdo kdr kds kkb kkk kkr kks koa kob kod kok koo kor kos kra krd krk kro krr krs ksa ksb ksd ksk kso ksr kss oaa oab oad oak oao oar oas ob- oba obb obd obk obo obr obs oda odb odd odo odr ods oka okb okd okk oko okr oks oo- ooa oob ood ook ooo oor oos or- ora orb ord ork oro orr ors os- osa osb osd osk oso osr oss ra- raa rab rad rak rao rar ras rba rbb rbd rbk rbo rbr rbs rda rdb rdd rdo rdr rds rkb rkk rko rks roa rob rod rok roo ror ros rra rrb rrd rrk rrr rrs rsa rsb rsd rsk rso rsr rss saa sab sad sak sao sar sas sba sbb sbd sbk sbo sbr sbs sda sdb sdd sdk sdo sdr sds sk- ska skb skd skk sko skr sks soa sob sod sok soo sor sos sr- sra srb srd srk sro srr srs ss- ssa ssb ssd ssk sso ssr sss