-er a-a a-b aaa aab aad aae aan aar ab- aba abb abd abe abn abr ad- ada adb add ade adn adr aea aeb aed aee aen aer an- ana anb and ane ann anr ar- ara arb ard are arn arr baa bab bad bae ban bar bba bbb bbd bbe bbn bbr bda bdb bdd bde bdr be- bea beb bed bee ben ber bna bnb bnd bne bnn bnr bra brb brd bre brn brr daa dab dad dae dan dar dba dbb dbd dbe dbn dbr dda ddb ddd dde ddn ddr de- dea deb ded dee den der dna dnb dnd dne dnn dnr dra drb drd dre drn drr eaa eab ead eae ean ear eba ebb ebd ebe ebn ebr ed- eda edb edd ede edn edr eea eeb eed eee een eer en- ena enb end ene enn enr era erb erd ere ern err naa nab nad nae nan nar nba nbb nbd nbe nbn nbr nda ndb ndd nde ndn ndr ne- nea neb ned nee nen ner nna nnb nne nnn nra nrb nrd nre nrn nrr ra- raa rab rad rae ran rar rba rbb rbd rbe rbn rbr rda rdb rdd rde rdn rdr re- rea reb red ree ren rer rna rnb rnd rnn rnr rra rrb rrd rrn rrr