a-a a-b aaa aab aag aao aay ab- aba abb abg abo aby ag- aga agb agg ago agy aoa aob aog aoo ay- aya ayo baa bab bag bao bay bba bbb bbg bbo bby bga bgb bgg bgo boa bob bog boo boy by- bya byg byo gaa gab gag gao gay gba gbg gbo gby gga ggb ggg ggo goa gob gog goo goy gy- gya gyb gyo oaa oab oag oao ob- oba obb obg obo oby oga ogg ogo ogy oo- ooa oob oog ooo oya oyo yaa yab yag yao yay ybg yby yga ygo yob yog yoo yoy yyb yyg yyy