a-a a-b a-t aaa aab aad aar aas aat ab- aba abb abd abr abs abt ad- ada adb add adr ads adt ar- ara arb ard arr ars art as- asa asb asd asr ass ast at- ata atb atd atr ats att baa bab bad bar bas bat bba bbb bbd bbr bbs bbt bda bdb bdd bdr bds bdt bra brb brd brr brs brt bsa bsb bsd bsr bss bst bta btb btd btr bts btt daa dab dad dar das dat dba dbb dbd dbr dbs dbt dda ddb ddd ddr dds ddt dra drb drd drr drs drt dsa dsb dsd dsr dss dst dta dtb dtd dtr dts dtt ra- raa rab rad rar ras rat rba rbb rbd rbr rbs rbt rda rdb rdd rdr rds rdt rra rrb rrd rrr rrs rrt rsa rsb rsd rsr rss rst rta rtb rtd rtr rts rtt saa sab sad sar sas sat sba sbb sbd sbr sbs sbt sda sdb sdd sdr sds sdt sr- sra srb srd srr srs srt ss- ssa ssb ssd ssr sss sst sta stb std str sts stt taa tab tad tar tas tat tba tbb tbd tbr tbs tbt tda tdb tdd tdr tds tdt tra trb trd trr trs trt tsa tsb tsd tsr tss tst tta ttb ttd ttr tts ttt