-er a-a a-b aaa aab aad aae aag aar ab- aba abb abd abe abg abr ad- ada adb add ade adg adr aea aeb aed aee aeg aer ag- aga agb agd age agg agr ar- ara arb ard are arg arr baa bab bad bae bag bar bba bbb bbd bbe bbg bbr bda bdb bdd bde bdg bdr be- bea beb bed bee beg ber bga bgb bgd bge bgg bgr bra brb brd bre brg brr daa dab dad dae dag dar dba dbb dbd dbe dbg dbr dda ddb ddd dde ddg ddr de- dea deb ded dee deg der dga dgd dge dgg dgr dra drb drd dre drg drr eaa eab ead eae eag ear eba ebb ebd ebe ebg ebr ed- eda edb edd ede edg edr eea eeb eed eee eeg eer ega egb egd ege egg egr era erb erd ere erg err g-d gaa gab gad gae gag gar gba gbd gbe gbg gbr gda gdb gdd gde gdr ge- gea geb ged gee geg ger gga ggb ggd ggg ggr gra grb grd gre grg grr ra- raa rab rad rae rag rar rba rbb rbd rbe rbg rbr rda rdb rdd rde rdg rdr re- rea reb red ree reg rer rga rgb rgd rge rgg rgr rra rrb rrd rrg rrr