a-a a-b a-t aaa aab aad aao aar aat ab- aba abb abd abo abr abt ad- ada adb add ado adr adt aoa aob aod aoo aor aot ar- ara arb ard aro arr art at- ata atb atd ato atr att baa bab bad bao bar bat bba bbb bbd bbo bbr bbt bda bdb bdd bdo bdr bdt boa bob bod boo bor bot bra brb brd bro brr brt bta btb btd bto btr btt daa dab dad dao dar dat dba dbb dbd dbo dbr dbt dda ddb ddd ddo ddr ddt doa dob dod doo dor dot dra drb drd dro drr drt dta dtb dtd dto dtr dtt oaa oab oad oao oar oat ob- oba obb obd obo obr obt oda odb odd odo odr odt oo- ooa oob ood ooo oor oot or- ora orb ord oro orr ort ot- ota otb otd oto otr ott ra- raa rab rad rao rar rat rba rbb rbd rbo rbr rbt rda rdb rdd rdo rdr rdt roa rob rod roo ror rot rra rrb rrd rrr rrt rta rtb rtd rto rtr rtt taa tab tad tao tar tat tba tbb tbd tbo tbr tbt tda tdb tdd tdo tdr tdt to- toa tob tod too tor tot tra trb trd tro trr trt tta ttb ttd tto ttr ttt