-er a-a a-b a-t aaa aab aae aag aan aar aat ab- aba abb abe abg abn abr abt aea aeb aee aeg aen aer aet ag- aga agb age agg agn agr agt an- ana anb ane ang ann anr ant ar- ara arb are arg arn arr art at- ata atb ate atg atn atr att baa bab bae bag ban bar bat bba bbb bbe bbg bbn bbr bbt be- bea beb bee beg ben ber bet bga bgb bge bgg bgn bgr bgt bna bnb bne bng bnn bnr bnt bra brb bre brg brn brr brt bta btb bte btg btn btr btt eaa eab eae eag ean ear eat eba ebb ebe ebg ebn ebr ebt eea eeb eee eeg een eer eet ega egb ege egg egn egr egt en- ena enb ene eng enn enr ent era erb ere erg ern err ert eta etb ete etg etn etr ett gaa gab gae gag gan gar gat gba gbe gbg gbn gbr gbt ge- gea geb gee geg gen ger get gga ggb ggg ggn ggr ggt gna gnb gne gnn gnr gnt gra grb gre grg grn grr grt gta gtb gte gtg gtn gtr gtt naa nab nae nag nan nar nat nba nbb nbe nbg nbn nbr nbt ne- nea neb nee neg nen ner net nga ngb nge ngg ngn ngt nna nnb nne nng nnn nnt nra nrb nre nrg nrn nrr nrt nta ntb nte ntg ntn ntr ntt ra- raa rab rae rag ran rar rat rba rbb rbe rbg rbn rbr rbt re- rea reb ree reg ren rer ret rga rgb rge rgg rgn rgr rgt rna rnb rng rnn rnr rnt rra rrb rrg rrn rrr rrt rta rtb rte rtg rtn rtr rtt taa tab tae tag tan tar tat tba tbb tbe tbg tbn tbr tbt te- tea teb tee teg ten ter tet tga tgb tge tgg tgn tgr tgt tna tnb tne tng tnn tnr tnt tra trb tre trg trn trr trt tta ttb tte ttg ttn ttr ttt