a-a a-b a-c aaa aab aac aad aan aar ab- aba abb abc abd abn abr ac- aca acb acc acd acn acr ad- ada adb adc add adn adr an- ana anb anc and ann anr ar- ara arb arc ard arn arr baa bab bac bad ban bar bba bbb bbc bbd bbn bbr bca bcb bcc bcd bcn bcr bda bdb bdc bdd bdr bna bnb bnc bnd bnn bnr bra brb brd brn brr c-- caa cab cac cad can car cba cbb cbc cbd cbn cbr cca ccb ccc ccd ccn ccr cda cdb cdc cdd cdn cdr cn- cna cnb cnc cnd cnn cnr cra crb crc crd crn crr daa dab dac dad dan dar dba dbb dbc dbd dbn dbr dca dcb dcc dcd dcn dcr dda ddb ddc ddd ddn ddr dna dnb dnc dnd dnn dnr dra drb drc drd drn drr naa nab nac nad nan nar nba nbb nbc nbd nbn nbr nca ncb ncc ncd ncn ncr nda ndb ndc ndd ndn ndr nna nnb nnc nnn nra nrb nrc nrd nrn nrr ra- raa rab rac rad ran rar rba rbb rbc rbd rbn rbr rca rcb rcc rcd rcn rcr rda rdb rdc rdd rdn rdr rna rnb rnc rnd rnn rnr rra rrb rrc rrd rrn rrr