a-a a-b a-c aaa aab aac aag aan aar ab- aba abb abc abg abn abr ac- aca acb acc acg acn acr ag- aga agb agc agg agn agr an- ana anb anc ang ann anr ar- ara arb arc arg arn arr baa bab bac bag ban bar bba bbb bbc bbg bbn bbr bca bcb bcc bcg bcn bcr bga bgb bgc bgg bgn bgr bna bnb bnc bng bnn bnr bra brb brg brn brr c-- caa cab cac cag can car cba cbb cbc cbg cbn cbr cca ccb ccc ccg ccn ccr cga cgb cgc cgg cgn cgr cn- cna cnb cnc cng cnn cnr cra crb crc crg crn crr gaa gab gac gag gan gar gba gbc gbg gbn gbr gca gcb gcc gcg gcn gcr gga ggb ggc ggg ggn ggr gna gnb gnc gnn gnr gra grb grc grg grn grr naa nab nac nag nan nar nba nbb nbc nbg nbn nbr nca ncb ncc ncg ncn ncr nga ngb ngc ngg ngn nna nnb nnc nng nnn nra nrb nrc nrg nrn nrr ra- raa rab rac rag ran rar rba rbb rbc rbg rbn rbr rca rcb rcc rcg rcn rcr rga rgb rgc rgg rgn rgr rna rnb rnc rng rnn rnr rra rrb rrc rrg rrn rrr