a-a a-b aaa aab aae aag aas ab- aba abb abe abg abs aea aeb aee aeg aes ag- aga agb age agg ags as- asa asb ase asg ass baa bab bae bag bas bba bbb bbe bbg bbs be- bea beb bee beg bes bga bgb bge bgg bgs bsa bsb bse bsg bss eaa eab eae eag eas eba ebb ebe ebg ebs eea eeb eee eeg ees ega egb ege egg egs es- esa esb ese esg ess gaa gab gae gag gas gba gbe gbg gbs ge- gea geb gee geg ges gga ggb ggg ggs gsa gsb gse gsg gss saa sab sae sag sas sba sbb sbe sbg sbs se- sea seb see seg ses sga sgb sge sgg sgs ss- ssa ssb sse ssg sss