a-a a-b a-t aaa aab aad aan aar aat ab- aba abb abd abn abr abt ad- ada adb add adn adr adt an- ana anb and ann anr ant ar- ara arb ard arn arr art at- ata atb atd atn atr att baa bab bad ban bar bat bba bbb bbd bbn bbr bbt bda bdb bdd bdr bdt bna bnb bnd bnn bnr bnt bra brb brd brn brr brt bta btb btd btn btr btt daa dab dad dan dar dat dba dbb dbd dbn dbr dbt dda ddb ddd ddn ddr ddt dna dnb dnd dnn dnr dnt dra drb drd drn drr drt dta dtb dtd dtn dtr dtt naa nab nad nan nar nat nba nbb nbd nbn nbr nbt nda ndb ndd ndn ndr ndt nna nnb nnn nnt nra nrb nrd nrn nrr nrt nta ntb ntd ntn ntr ntt ra- raa rab rad ran rar rat rba rbb rbd rbn rbr rbt rda rdb rdd rdn rdr rdt rna rnb rnd rnn rnr rnt rra rrb rrd rrn rrr rrt rta rtb rtd rtn rtr rtt taa tab tad tan tar tat tba tbb tbd tbn tbr tbt tda tdb tdd tdn tdr tdt tna tnb tnd tnn tnr tnt tra trb trd trn trr trt tta ttb ttd ttn ttr ttt