-er a-a a-b aaa aab aae aag aan aar ab- aba abb abe abg abn abr aea aeb aee aeg aen aer ag- aga agb age agg agn agr an- ana anb ane ang ann anr ar- ara arb are arg arn arr baa bab bae bag ban bar bba bbb bbe bbg bbn bbr be- bea beb bee beg ben ber bga bgb bge bgg bgn bgr bna bnb bne bng bnn bnr bra brb bre brg brn brr eaa eab eae eag ean ear eba ebb ebe ebg ebn ebr eea eeb eee eeg een eer ega egb ege egg egn egr en- ena enb ene eng enn enr era erb ere erg ern err gaa gab gae gag gan gar gba gbe gbg gbn gbr ge- gea geb gee geg gen ger gga ggb ggg ggn ggr gna gnb gne gnn gnr gra grb gre grg grn grr naa nab nae nag nan nar nba nbb nbe nbg nbn nbr ne- nea neb nee neg nen ner nga ngb nge ngg ngn nna nnb nne nng nnn nra nrb nre nrg nrn nrr ra- raa rab rae rag ran rar rba rbb rbe rbg rbn rbr re- rea reb ree reg ren rer rga rgb rge rgg rgn rgr rna rnb rng rnn rnr rra rrb rrg rrn rrr