a-a a-b a-c aaa aab aac aad aak aan aar ab- aba abb abc abd abk abn abr ac- aca acb acc acd ack acn acr ad- ada adb adc add adk adn adr aka akb akc akd akk akn akr an- ana anb anc and ank ann anr ar- ara arb arc ard ark arn arr baa bab bac bad bak ban bar bba bbb bbc bbd bbk bbn bbr bca bcb bcc bcd bck bcn bcr bda bdb bdc bdd bdk bdr bka bkb bkc bkk bkn bkr bna bnb bnc bnd bnk bnn bnr bra brb brd brk brn brr c-- caa cab cac cad cak can car cba cbb cbc cbd cbk cbn cbr cca ccb ccc ccd cck ccn ccr cda cdb cdc cdd cdk cdn cdr cka ckb ckc ckd cn- cna cnb cnc cnd cnn cnr cra crb crc crd crk crn crr daa dab dac dad dak dan dar dba dbb dbc dbd dbk dbn dbr dca dcb dcc dcd dck dcn dcr dda ddb ddc ddd ddk ddn ddr dka dkb dkc dkk dkr dna dnb dnc dnd dnk dnn dnr dra drb drc drd drk drn drr ka- kaa kab kac kad kak kan kar kba kbb kbc kbd kbk kbn kbr kca kcb kcc kcd kck kcn kcr kda kdb kdc kdk kdr kkb kkc kkk kkn kkr kn- kna knc knd knk knn knr kra krc krd krk krn krr naa nab nac nad nak nan nar nba nbb nbc nbd nbk nbn nbr nca ncb ncc ncd nck ncn ncr nda ndb ndc ndd ndk ndn ndr nka nkc nkk nkn nkr nna nnb nnc nnk nnn nra nrb nrc nrd nrk nrn nrr ra- raa rab rac rad rak ran rar rba rbb rbc rbd rbk rbn rbr rca rcb rcc rcd rcn rcr rda rdb rdc rdd rdn rdr rkb rkc rkk rna rnb rnc rnd rnn rnr rra rrb rrc rrd rrk rrn rrr