-er a-a a-b a-c aaa aab aac aae aag aar ab- aba abb abc abe abg abr ac- aca acb acc ace acg acr aea aeb aec aee aeg aer ag- aga agb agc age agg agr ar- ara arb arc are arg arr baa bab bac bae bag bar bba bbb bbc bbe bbg bbr bca bcb bcc bce bcg bcr be- bea beb bec bee beg ber bga bgb bgc bge bgg bgr bra brb bre brg brr c-- caa cab cac cae cag car cba cbb cbc cbe cbg cbr cca ccb ccc cce ccg ccr ce- cea ceb cec cee ceg cer cga cgb cgc cge cgg cgr cra crb crc cre crg crr eaa eab eac eae eag ear eba ebb ebc ebe ebg ebr ec- eca ecb ecc ece ecg ecr eea eeb eec eee eeg eer ega egb egc ege egg egr era erb erc ere erg err gaa gab gac gae gag gar gba gbc gbe gbg gbr gca gcb gcc gce gcg gcr ge- gea geb gec gee geg ger gga ggb ggc ggg ggr gra grb grc gre grg grr ra- raa rab rac rae rag rar rba rbb rbc rbe rbg rbr rca rcb rcc rce rcg rcr re- rea reb rec ree reg rer rga rgb rgc rge rgg rgr rra rrb rrc rrg rrr