-er a-a a-b a-t aaa aab aad aae aar aas aat ab- aba abb abd abe abr abs abt ad- ada adb add ade adr ads adt aea aeb aed aee aer aes aet ar- ara arb ard are arr ars art as- asa asb asd ase asr ass ast at- ata atb atd ate atr ats att baa bab bad bae bar bas bat bba bbb bbd bbe bbr bbs bbt bda bdb bdd bde bdr bds bdt be- bea beb bed bee ber bes bet bra brb brd bre brr brs brt bsa bsb bsd bse bsr bss bst bta btb btd bte btr bts btt daa dab dad dae dar das dat dba dbb dbd dbe dbr dbs dbt dda ddb ddd dde ddr dds ddt de- dea deb ded dee der des det dra drb drd dre drr drs drt dsa dsb dsd dse dsr dss dst dta dtb dtd dte dtr dts dtt eaa eab ead eae ear eas eat eba ebb ebd ebe ebr ebs ebt ed- eda edb edd ede edr eds edt eea eeb eed eee eer ees eet era erb erd ere err ers ert es- esa esb esd ese esr ess est eta etb etd ete etr ets ett ra- raa rab rad rae rar ras rat rba rbb rbd rbe rbr rbs rbt rda rdb rdd rde rdr rds rdt re- rea reb red ree rer res ret rra rrb rrd rrr rrs rrt rsa rsb rsd rse rsr rss rst rta rtb rtd rte rtr rts rtt saa sab sad sae sar sas sat sba sbb sbd sbe sbr sbs sbt sda sdb sdd sde sdr sds sdt se- sea seb sed see ser ses set sr- sra srb srd sre srr srs srt ss- ssa ssb ssd sse ssr sss sst sta stb std ste str sts stt taa tab tad tae tar tas tat tba tbb tbd tbe tbr tbs tbt tda tdb tdd tde tdr tds tdt te- tea teb ted tee ter tes tet tra trb trd tre trr trs trt tsa tsb tsd tse tsr tss tst tta ttb ttd tte ttr tts ttt