-er a-a a-b a-c a-t aaa aab aac aad aae aar aat ab- aba abb abc abd abe abr abt ac- aca acb acc acd ace acr act ad- ada adb adc add ade adr adt aea aeb aec aed aee aer aet ar- ara arb arc ard are arr art at- ata atb atc atd ate atr att baa bab bac bad bae bar bat bba bbb bbc bbd bbe bbr bbt bca bcb bcc bcd bce bcr bct bda bdb bdc bdd bde bdr bdt be- bea beb bec bed bee ber bet bra brb brd bre brr brt bta btb btc btd bte btr btt c-- caa cab cac cad cae car cat cba cbb cbc cbd cbe cbr cbt cca ccb ccc ccd cce ccr cct cda cdb cdc cdd cde cdr cdt ce- cea ceb cec ced cee cer cet cra crb crc crd cre crr crt cta ctb ctc ctd cte ctr ctt daa dab dac dad dae dar dat dba dbb dbc dbd dbe dbr dbt dca dcb dcc dcd dce dcr dct dda ddb ddc ddd dde ddr ddt de- dea deb dec ded dee der det dra drb drc drd dre drr drt dta dtb dtc dtd dte dtr dtt eaa eab eac ead eae ear eat eba ebb ebc ebd ebe ebr ebt ec- eca ecb ecc ecd ece ecr ect ed- eda edb edc edd ede edr edt eea eeb eec eed eee eer eet era erb erc erd ere err ert eta etb etc etd ete etr ett ra- raa rab rac rad rae rar rat rba rbb rbc rbd rbe rbr rbt rca rcb rcc rcd rce rcr rct rda rdb rdc rdd rde rdr rdt re- rea reb rec red ree rer ret rra rrb rrc rrd rrr rrt rta rtb rtc rtd rte rtr rtt taa tab tac tad tae tar tat tba tbb tbc tbd tbe tbr tbt tca tcb tcc tcd tce tcr tct tda tdb tdc tdd tde tdr tdt te- tea teb tec ted tee ter tet tra trb trc trd tre trr trt tta ttb ttc ttd tte ttr ttt