-er a-a a-b aaa aab aad aae aak aan aar ab- aba abb abd abe abk abn abr ad- ada adb add ade adk adn adr aea aeb aed aee aek aen aer aka akb akd ake akk akn akr an- ana anb and ane ank ann anr ar- ara arb ard are ark arn arr baa bab bad bae bak ban bar bba bbb bbd bbe bbk bbn bbr bda bdb bdd bde bdk bdr be- bea beb bed bee bek ben ber bka bkb bke bkk bkn bkr bna bnb bnd bne bnk bnn bnr bra brb brd bre brk brn brr daa dab dad dae dak dan dar dba dbb dbd dbe dbk dbn dbr dda ddb ddd dde ddk ddn ddr de- dea deb ded dee dek den der dka dkb dke dkk dkr dna dnb dnd dne dnk dnn dnr dra drb drd dre drk drn drr eaa eab ead eae eak ean ear eba ebb ebd ebe ebk ebn ebr ed- eda edb edd ede edk edn edr eea eeb eed eee eek een eer eka ekb ekd eke ekr en- ena enb end ene enk enn enr era erb erd ere erk ern err ka- kaa kab kad kae kak kan kar kba kbb kbd kbe kbk kbn kbr kda kdb kde kdk kdr ke- kea keb ked kee kek ken ker kkb kke kkk kkn kkr kn- kna knd kne knk knn knr kra krd krk krn krr naa nab nad nae nak nan nar nba nbb nbd nbe nbk nbn nbr nda ndb ndd nde ndk ndn ndr ne- nea neb ned nee nek nen ner nka nke nkk nkn nkr nna nnb nne nnk nnn nra nrb nrd nre nrk nrn nrr ra- raa rab rad rae rak ran rar rba rbb rbd rbe rbk rbn rbr rda rdb rdd rde rdn rdr re- rea reb red ree rek ren rer rkb rke rkk rna rnb rnd rnn rnr rra rrb rrd rrk rrn rrr