a-a a-b aaa aab aad aak aao aar aas aav ab- aba abb abd abk abo abr abs abv ad- ada adb add adk ado adr ads adv aka akb akd akk ako akr aks akv aoa aob aod aok aoo aor aos aov ar- ara arb ard ark aro arr ars arv as- asa asb asd ask aso asr ass asv av- ava avb avd avk avo avr avs baa bab bad bak bao bar bas bav bba bbb bbd bbk bbo bbr bbs bda bdb bdd bdk bdo bdr bds bdv bka bkb bkk bko bkr bks bkv boa bob bod bok boo bor bos bov bra brb brd brk bro brr brs brv bsa bsb bsd bsk bso bsr bss bsv bva bvb bvd bvk bvo bvr bvs bvv daa dab dad dak dao dar das dav dba dbb dbd dbk dbo dbr dbs dbv dda ddb ddd ddk ddo ddr dds dka dkb dkk dko dkr dks doa dob dod dok doo dor dos dov dra drb drd drk dro drr drs drv dsa dsb dsd dsk dso dsr dss dsv dva dvb dvd dvk dvr dvs ka- kaa kab kad kak kao kar kas kav kba kbb kbd kbk kbo kbr kbs kda kdb kdk kdo kdr kds kkb kkk kkr kks kkv koa kob kod kok koo kor kos kra krd krk kro krr krs krv ksa ksb ksd ksk kso ksr kss ksv kva kvb kvk kvo kvr kvs kvv oaa oab oad oak oao oar oas oav ob- oba obb obd obk obo obr obs obv oda odb odd odo odr ods odv oka okb okd okk oko okr oks oo- ooa oob ood ook ooo oor oos oov or- ora orb ord ork oro orr ors orv os- osa osb osd osk oso osr oss osv ov- ova ovb ovd ovo ovs ovv ra- raa rab rad rak rao rar ras rav rba rbb rbd rbk rbo rbr rbs rda rdb rdd rdo rdr rds rdv rkb rkk rko rks rkv roa rob rod rok roo ror ros rov rra rrb rrd rrk rrr rrs rsa rsb rsd rsk rso rsr rss rsv rva rvb rvd rvo rvr rvs rvv saa sab sad sak sao sar sas sav sba sbb sbd sbk sbo sbr sbs sbv sda sdb sdd sdk sdo sdr sds sdv sk- ska skb skd skk sko skr sks soa sob sod sok soo sor sos sov sr- sra srb srd srk sro srr srs srv ss- ssa ssb ssd ssk sso ssr sss ssv sva svb svd svk svo svr svs svv v-a vaa vab vad vak vao var vas vav vba vbd vbk vbo vbr vbs vbv vdb vdd vdk vdo vdr vds vdv vka vkb voa vob vod vok voo vor vos vov vra vrb vrd vrk vrr vrs vsa vsb vsd vsk vso vsr vss vsv vva vvb vvo vvr vvs vvv