-er a-a a-b a-c aaa aab aac aad aae aak aan aar ab- aba abb abc abd abe abk abn abr ac- aca acb acc acd ace ack acn acr ad- ada adb adc add ade adk adn adr aea aeb aec aed aee aek aen aer aka akb akc akd ake akk akn akr an- ana anb anc and ane ank ann anr ar- ara arb arc ard are ark arn arr baa bab bac bad bae bak ban bar bba bbb bbc bbd bbe bbk bbn bbr bca bcb bcc bcd bce bck bcn bcr bda bdb bdc bdd bde bdk bdr be- bea beb bec bed bee bek ben ber bka bkb bkc bke bkk bkn bkr bna bnb bnc bnd bne bnk bnn bnr bra brb brd bre brk brn brr c-- caa cab cac cad cae cak can car cba cbb cbc cbd cbe cbk cbn cbr cca ccb ccc ccd cce cck ccn ccr cda cdb cdc cdd cde cdk cdn cdr ce- cea ceb cec ced cee cek cen cer cka ckb ckc ckd cn- cna cnb cnc cnd cne cnn cnr cra crb crc crd cre crk crn crr daa dab dac dad dae dak dan dar dba dbb dbc dbd dbe dbk dbn dbr dca dcb dcc dcd dce dck dcn dcr dda ddb ddc ddd dde ddk ddn ddr de- dea deb dec ded dee dek den der dka dkb dkc dke dkk dkr dna dnb dnc dnd dne dnk dnn dnr dra drb drc drd dre drk drn drr eaa eab eac ead eae eak ean ear eba ebb ebc ebd ebe ebk ebn ebr ec- eca ecb ecc ecd ece eck ecn ecr ed- eda edb edc edd ede edk edn edr eea eeb eec eed eee eek een eer eka ekb ekc ekd eke ekr en- ena enb enc end ene enk enn enr era erb erc erd ere erk ern err ka- kaa kab kac kad kae kak kan kar kba kbb kbc kbd kbe kbk kbn kbr kca kcb kcc kcd kce kck kcn kcr kda kdb kdc kde kdk kdr ke- kea keb kec ked kee kek ken ker kkb kkc kke kkk kkn kkr kn- kna knc knd kne knk knn knr kra krc krd krk krn krr naa nab nac nad nae nak nan nar nba nbb nbc nbd nbe nbk nbn nbr nca ncb ncc ncd nce nck ncn ncr nda ndb ndc ndd nde ndk ndn ndr ne- nea neb nec ned nee nek nen ner nka nkc nke nkk nkn nkr nna nnb nnc nne nnk nnn nra nrb nrc nrd nre nrk nrn nrr ra- raa rab rac rad rae rak ran rar rba rbb rbc rbd rbe rbk rbn rbr rca rcb rcc rcd rce rcn rcr rda rdb rdc rdd rde rdn rdr re- rea reb rec red ree rek ren rer rkb rkc rke rkk rna rnb rnc rnd rnn rnr rra rrb rrc rrd rrk rrn rrr