-er a-a a-b a-t aaa aab aad aae aan aar aat ab- aba abb abd abe abn abr abt ad- ada adb add ade adn adr adt aea aeb aed aee aen aer aet an- ana anb and ane ann anr ant ar- ara arb ard are arn arr art at- ata atb atd ate atn atr att baa bab bad bae ban bar bat bba bbb bbd bbe bbn bbr bbt bda bdb bdd bde bdr bdt be- bea beb bed bee ben ber bet bna bnb bnd bne bnn bnr bnt bra brb brd bre brn brr brt bta btb btd bte btn btr btt daa dab dad dae dan dar dat dba dbb dbd dbe dbn dbr dbt dda ddb ddd dde ddn ddr ddt de- dea deb ded dee den der det dna dnb dnd dne dnn dnr dnt dra drb drd dre drn drr drt dta dtb dtd dte dtn dtr dtt eaa eab ead eae ean ear eat eba ebb ebd ebe ebn ebr ebt ed- eda edb edd ede edn edr edt eea eeb eed eee een eer eet en- ena enb end ene enn enr ent era erb erd ere ern err ert eta etb etd ete etn etr ett naa nab nad nae nan nar nat nba nbb nbd nbe nbn nbr nbt nda ndb ndd nde ndn ndr ndt ne- nea neb ned nee nen ner net nna nnb nne nnn nnt nra nrb nrd nre nrn nrr nrt nta ntb ntd nte ntn ntr ntt ra- raa rab rad rae ran rar rat rba rbb rbd rbe rbn rbr rbt rda rdb rdd rde rdn rdr rdt re- rea reb red ree ren rer ret rna rnb rnd rnn rnr rnt rra rrb rrd rrn rrr rrt rta rtb rtd rte rtn rtr rtt taa tab tad tae tan tar tat tba tbb tbd tbe tbn tbr tbt tda tdb tdd tde tdn tdr tdt te- tea teb ted tee ten ter tet tna tnb tnd tne tnn tnr tnt tra trb trd tre trn trr trt tta ttb ttd tte ttn ttr ttt