a-a a-b aaa aab aag aah aan aao ab- aba abb abg abh abn abo ag- aga agb agg agh agn ago aha ahb ahg ahh ahn aho an- ana anb ang anh ann ano aoa aob aog aoh aon aoo baa bab bag bah ban bao bba bbb bbg bbh bbn bbo bga bgb bgg bgh bgn bgo bha bhb bhg bhh bho bna bnb bng bnn bno boa bob bog boh bon boo gaa gab gag gah gan gao gba gbg gbh gbn gbo gga ggb ggg ggh ggn ggo gha ghb ghg ghh ghn gho gna gnb gnn gno goa gob gog goh gon goo haa hab hag hah han hao hba hbb hbg hbh hbn hbo hga hgb hgg hgh hgn hgo hha hhb hhg hhh hhn hho hna hnb hng hnh hnn hno hoa hob hog hoh hon hoo naa nab nag nah nan nao nba nbb nbg nbn nbo nga ngb ngg ngh ngn ngo nha nhb nhg nhh nhn nna nnb nng nnh nnn nno no- noa nob nog noh non noo oaa oab oag oah oan oao ob- oba obb obg obh obn obo oga ogg ogh ogn ogo oha ohg ohh ohn oho on- ona onb ong onh onn ono oo- ooa oob oog ooh oon ooo