a-a a-b aaa aab aad aak aar aas ab- aba abb abd abk abr abs ad- ada adb add adk adr ads aka akb akd akk akr aks ar- ara arb ard ark arr ars as- asa asb asd ask asr ass baa bab bad bak bar bas bba bbb bbd bbk bbr bbs bda bdb bdd bdk bdr bds bka bkb bkk bkr bks bra brb brd brk brr brs bsa bsb bsd bsk bsr bss daa dab dad dak dar das dba dbb dbd dbk dbr dbs dda ddb ddd ddk ddr dds dka dkb dkk dkr dks dra drb drd drk drr drs dsa dsb dsd dsk dsr dss ka- kaa kab kad kak kar kas kba kbb kbd kbk kbr kbs kda kdb kdk kdr kds kkb kkk kkr kks kra krd krk krr krs ksa ksb ksd ksk ksr kss ra- raa rab rad rak rar ras rba rbb rbd rbk rbr rbs rda rdb rdd rdr rds rkb rkk rks rra rrb rrd rrk rrr rrs rsa rsb rsd rsk rsr rss saa sab sad sak sar sas sba sbb sbd sbk sbr sbs sda sdb sdd sdk sdr sds sk- ska skb skd skk skr sks sr- sra srb srd srk srr srs ss- ssa ssb ssd ssk ssr sss