-er a-a a-b a-c a-t aaa aab aac aad aae aak aao aar aat ab- aba abb abc abd abe abk abo abr abt ac- aca acb acc acd ace ack aco acr act ad- ada adb adc add ade adk ado adr adt aea aeb aec aed aee aek aeo aer aet aka akb akc akd ake akk ako akr aoa aob aoc aod aoe aok aoo aor aot ar- ara arb arc ard are ark aro arr art at- ata atb atc atd ate ato atr att baa bab bac bad bae bak bao bar bat bba bbb bbc bbd bbe bbk bbo bbr bbt bca bcb bcc bcd bce bck bco bcr bct bda bdb bdc bdd bde bdk bdo bdr bdt be- bea beb bec bed bee bek beo ber bet bka bkb bkc bke bkk bko bkr bkt boa bob boc bod boe bok boo bor bot bra brb brd bre brk bro brr brt bta btb btc btd bte btk bto btr btt c-- caa cab cac cad cae cak cao car cat cba cbb cbc cbd cbe cbk cbo cbr cbt cca ccb ccc ccd cce cck cco ccr cct cda cdb cdc cdd cde cdk cdo cdr cdt ce- cea ceb cec ced cee cek ceo cer cet cka ckb ckc ckd cko ckt co- coa cob coc cod coe cok coo cor cot cra crb crc crd cre crk cro crr crt cta ctb ctc ctd cte ctk cto ctr ctt daa dab dac dad dae dak dao dar dat dba dbb dbc dbd dbe dbk dbo dbr dbt dca dcb dcc dcd dce dck dco dcr dct dda ddb ddc ddd dde ddk ddo ddr ddt de- dea deb dec ded dee dek deo der det dka dkb dkc dke dkk dko dkr dkt doa dob doc dod doe dok doo dor dot dra drb drc drd dre drk dro drr drt dta dtb dtc dtd dte dtk dto dtr dtt eaa eab eac ead eae eak eao ear eat eba ebb ebc ebd ebe ebk ebo ebr ebt ec- eca ecb ecc ecd ece eck eco ecr ect ed- eda edb edc edd ede edk edo edr edt eea eeb eec eed eee eek eeo eer eet eka ekb ekc ekd eke eko ekr ekt eo- eoa eob eoc eod eoe eok eoo eor eot era erb erc erd ere erk ero err ert eta etb etc etd ete etk eto etr ett k-t ka- kaa kab kac kad kae kak kao kar kat kba kbb kbc kbd kbe kbk kbo kbr kca kcb kcc kcd kce kck kcr kct kda kdb kdc kde kdk kdo kdr kdt ke- kea keb kec ked kee kek keo ker ket kkb kkc kke kkk kkr kkt koa kob koc kod koe kok koo kor kot kra krc krd krk kro krr krt kta ktb ktc kte ktk kto ktr ktt oaa oab oac oad oae oak oao oar oat ob- oba obb obc obd obe obk obo obr obt oc- oca ocb occ ocd ock oco ocr oct oda odb odc odd ode odo odr odt oea oeb oec oed oee oeo oer oet oka okb okc okd oke okk oko okr oo- ooa oob ooc ood ook ooo oor oot or- ora orb orc ord ore ork oro orr ort ot- ota otb otc otd ote otk oto otr ott ra- raa rab rac rad rae rak rao rar rat rba rbb rbc rbd rbe rbk 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 rek reo rer ret rkb rkc rke rkk rko rkt roa rob roc rod roe rok roo ror rot rra rrb rrc rrd rrk rrr rrt rta rtb rtc rtd rte rtk rto rtr rtt taa tab tac tad tae tak tao tar tat tba tbb tbc tbd tbe tbk tbo tbr tbt tca tcb tcc tcd tce tck tco tcr tct tda tdb tdc tdd tde tdk tdo tdr tdt te- tea teb tec ted tee tek teo ter tet tka tkb tkc tke tkk tko tkr tkt to- toa tob toc tod toe tok too tor tot tra trb trc trd tre trk tro trr trt tta ttb ttc ttd tte ttk tto ttr ttt