a-a a-b aaa aab aae aag aao ab- aba abb abe abg abo aea aeb aee aeg aeo ag- aga agb age agg ago aoa aob aoe aog aoo baa bab bae bag bao bba bbb bbe bbg bbo be- bea beb bee beg beo bga bgb bge bgg bgo boa bob boe bog boo eaa eab eae eag eao eba ebb ebe ebg ebo eea eeb eee eeg eeo ega egb ege egg ego eo- eoa eob eoe eog eoo gaa gab gae gag gao gba gbe gbg gbo ge- gea geb gee geg geo gga ggb ggg ggo goa gob goe gog goo oaa oab oae oag oao ob- oba obb obe obg obo oea oeb oee oeg oeo oga oge ogg ogo oo- ooa oob oog ooo