a-a a-b a-c a-t aaa aab aac aad aao aar aat ab- aba abb abc abd abo abr abt ac- aca acb acc acd aco acr act ad- ada adb adc add ado adr adt aoa aob aoc aod aoo aor aot ar- ara arb arc ard aro arr art at- ata atb atc atd ato atr att baa bab bac bad bao bar bat bba bbb bbc bbd bbo bbr bbt bca bcb bcc bcd bco bcr bct bda bdb bdc bdd bdo bdr bdt boa bob boc bod boo bor bot bra brb brd bro brr brt bta btb btc btd bto btr btt c-- caa cab cac cad cao car cat cba cbb cbc cbd cbo cbr cbt cca ccb ccc ccd cco ccr cct cda cdb cdc cdd cdo cdr cdt co- coa cob coc cod coo cor cot cra crb crc crd cro crr crt cta ctb ctc ctd cto ctr ctt daa dab dac dad dao dar dat dba dbb dbc dbd dbo dbr dbt dca dcb dcc dcd dco dcr dct dda ddb ddc ddd ddo ddr ddt doa dob doc dod doo dor dot dra drb drc drd dro drr drt dta dtb dtc dtd dto dtr dtt oaa oab oac oad oao oar oat ob- oba obb obc obd obo obr obt oc- oca ocb occ ocd oco ocr oct oda odb odc odd odo odr odt oo- ooa oob ooc ood ooo oor oot or- ora orb orc ord oro orr ort ot- ota otb otc otd oto otr ott ra- raa rab rac rad rao rar rat rba rbb rbc rbd rbo rbr rbt rca rcb rcc rcd rco rcr rct rda rdb rdc rdd rdo rdr rdt roa rob roc rod roo ror rot rra rrb rrc rrd rrr rrt rta rtb rtc rtd rto rtr rtt taa tab tac tad tao tar tat tba tbb tbc tbd tbo tbr tbt tca tcb tcc tcd tco tcr tct tda tdb tdc tdd tdo tdr tdt to- toa tob toc tod too tor tot tra trb trc trd tro trr trt tta ttb ttc ttd tto ttr ttt