a-a a-b a-c aaa aab aac aag aar ab- aba abb abc abg abr ac- aca acb acc acg acr ag- aga agb agc agg agr ar- ara arb arc arg arr baa bab bac bag bar bba bbb bbc bbg bbr bca bcb bcc bcg bcr bga bgb bgc bgg bgr bra brb brg brr c-- caa cab cac cag car cba cbb cbc cbg cbr cca ccb ccc ccg ccr cga cgb cgc cgg cgr cra crb crc crg crr gaa gab gac gag gar gba gbc gbg gbr gca gcb gcc gcg gcr gga ggb ggc ggg ggr gra grb grc grg grr ra- raa rab rac rag rar rba rbb rbc rbg rbr rca rcb rcc rcg rcr rga rgb rgc rgg rgr rra rrb rrc rrg rrr