-er a-a a-b a-c aaa aab aac aae aag aan aar ab- aba abb abc abe abg abn abr ac- aca acb acc ace acg acn acr aea aeb aec aee aeg aen aer ag- aga agb agc age agg agn agr an- ana anb anc ane ang ann anr ar- ara arb arc are arg arn arr baa bab bac bae bag ban bar bba bbb bbc bbe bbg bbn bbr bca bcb bcc bce bcg bcn bcr be- bea beb bec bee beg ben ber bga bgb bgc bge bgg bgn bgr bna bnb bnc bne bng bnn bnr bra brb bre brg brn brr c-- caa cab cac cae cag can car cba cbb cbc cbe cbg cbn cbr cca ccb ccc cce ccg ccn ccr ce- cea ceb cec cee ceg cen cer cga cgb cgc cge cgg cgn cgr cn- cna cnb cnc cne cng cnn cnr cra crb crc cre crg crn crr eaa eab eac eae eag ean ear eba ebb ebc ebe ebg ebn ebr ec- eca ecb ecc ece ecg ecn ecr eea eeb eec eee eeg een eer ega egb egc ege egg egn egr en- ena enb enc ene eng enn enr era erb erc ere erg ern err gaa gab gac gae gag gan gar gba gbc gbe gbg gbn gbr gca gcb gcc gce gcg gcn gcr ge- gea geb gec gee geg gen ger gga ggb ggc ggg ggn ggr gna gnb gnc gne gnn gnr gra grb grc gre grg grn grr naa nab nac nae nag nan nar nba nbb nbc nbe nbg nbn nbr nca ncb ncc nce ncg ncn ncr ne- nea neb nec nee neg nen ner nga ngb ngc nge ngg ngn nna nnb nnc nne nng nnn nra nrb nrc nre nrg nrn nrr ra- raa rab rac rae rag ran rar rba rbb rbc rbe rbg rbn rbr rca rcb rcc rce rcg rcn rcr re- rea reb rec ree reg ren rer rga rgb rgc rge rgg rgn rgr rna rnb rnc rng rnn rnr rra rrb rrc rrg rrn rrr