-er a-a a-b a-c a-t aaa aab aac aad aae aao aar aat ab- aba abb abc abd abe abo abr abt ac- aca acb acc acd ace aco acr act ad- ada adb adc add ade ado adr adt aea aeb aec aed aee aeo aer aet aoa aob aoc aod aoe aoo aor aot ar- ara arb arc ard are aro arr art at- ata atb atc atd ate ato atr att baa bab bac bad bae bao bar bat bba bbb bbc bbd bbe bbo bbr bbt bca bcb bcc bcd bce bco bcr bct bda bdb bdc bdd bde bdo bdr bdt be- bea beb bec bed bee beo ber bet boa bob boc bod boe boo bor bot bra brb brd bre bro brr brt bta btb btc btd bte bto btr btt c-- caa cab cac cad cae cao car cat cba cbb cbc cbd cbe cbo cbr cbt cca ccb ccc ccd cce cco ccr cct cda cdb cdc cdd cde cdo cdr cdt ce- cea ceb cec ced cee ceo cer cet co- coa cob coc cod coe coo cor cot cra crb crc crd cre cro crr crt cta ctb ctc ctd cte cto ctr ctt daa dab dac dad dae dao dar dat dba dbb dbc dbd dbe dbo dbr dbt dca dcb dcc dcd dce dco dcr dct dda ddb ddc ddd dde ddo ddr ddt de- dea deb dec ded dee deo der det doa dob doc dod doe doo dor dot dra drb drc drd dre dro drr drt dta dtb dtc dtd dte dto dtr dtt eaa eab eac ead eae eao ear eat eba ebb ebc ebd ebe ebo ebr ebt ec- eca ecb ecc ecd ece eco ecr ect ed- eda edb edc edd ede edo edr edt eea eeb eec eed eee eeo eer eet eo- eoa eob eoc eod eoe eoo eor eot era erb erc erd ere ero err ert eta etb etc etd ete eto etr ett oaa oab oac oad oae oao oar oat ob- oba obb obc obd obe obo obr obt oc- oca ocb occ ocd oco ocr oct oda odb odc odd ode odo odr odt oea oeb oec oed oee oeo oer oet oo- ooa oob ooc ood ooo oor oot or- ora orb orc ord ore oro orr ort ot- ota otb otc otd ote oto otr ott ra- raa rab rac rad rae rao rar rat rba rbb rbc rbd rbe rbo rbr rbt rca rcb rcc rcd rce rco rcr rct rda rdb rdc rdd rde rdo rdr rdt re- rea reb rec red ree reo rer ret roa rob roc rod roe roo ror rot rra rrb rrc rrd rrr rrt rta rtb rtc rtd rte rto rtr rtt taa tab tac tad tae tao tar tat tba tbb tbc tbd tbe tbo tbr tbt tca tcb tcc tcd tce tco tcr tct tda tdb tdc tdd tde tdo tdr tdt te- tea teb tec ted tee teo ter tet to- toa tob toc tod toe too tor tot tra trb trc trd tre tro trr trt tta ttb ttc ttd tte tto ttr ttt