-er a-a a-b aaa aab aae aag aar aas ab- aba abb abe abg abr abs aea aeb aee aeg aer aes ag- aga agb age agg agr ags ar- ara arb are arg arr ars as- asa asb ase asg asr ass baa bab bae bag bar bas bba bbb bbe bbg bbr bbs be- bea beb bee beg ber bes bga bgb bge bgg bgr bgs bra brb bre brg brr brs bsa bsb bse bsg bsr bss eaa eab eae eag ear eas eba ebb ebe ebg ebr ebs eea eeb eee eeg eer ees ega egb ege egg egr egs era erb ere erg err ers es- esa esb ese esg esr ess gaa gab gae gag gar gas gba gbe gbg gbr gbs ge- gea geb gee geg ger ges gga ggb ggg ggr ggs gra grb gre grg grr grs gsa gsb gse gsg gsr gss ra- raa rab rae rag rar ras rba rbb rbe rbg rbr rbs re- rea reb ree reg rer res rga rgb rge rgg rgr rgs rra rrb rrg rrr rrs rsa rsb rse rsg rsr rss saa sab sae sag sar sas sba sbb sbe sbg sbr sbs se- sea seb see seg ser ses sga sgb sge sgg sgr sgs sr- sra srb sre srg srr srs ss- ssa ssb sse ssg ssr sss