a-a a-b aaa aab aag aak aao ab- aba abb abg abk abo ag- aga agb agg agk ago aka akb akg akk ako aoa aob aog aok aoo baa bab bag bak bao bba bbb bbg bbk bbo bga bgb bgg bgk bgo bka bkb bkg bkk bko boa bob bog bok boo gaa gab gag gak gao gba gbg gbk gbo gga ggb ggg ggo gka gkb gko goa gob gog gok goo ka- kaa kab kag kak kao kba kbb kbk kbo kga kgb kgo kkb kkk koa kob kog kok koo oaa oab oag oak oao ob- oba obb obg obk obo oga ogg ogo oka okb okg okk oko oo- ooa oob oog ook ooo