a-a a-b a-c aaa aab aac aag aao aau ab- aba abb abc abg abo abu ac- aca acb acc acg aco acu ag- aga agb agc agg ago agu aoa aob aoc aog aoo aou au- aua aub auc aug auo b-u baa bab bac bag bao bau bba bbb bbc bbg bbo bbu bca bcb bcc bcg bco bcu bga bgb bgc bgg bgo bgu boa bob boc bog boo bou bua bub buc bug buo buu c-- caa cab cac cag cao cau cba cbb cbc cbg cbo cbu cca ccb ccc ccg cco ccu cga cgb cgc cgg cgo cgu co- coa cob coc cog coo cou cua cub cuc cug cuo cuu gaa gab gac gag gao gau gba gbc gbg gbo gbu gca gcb gcc gcg gco gcu gga ggb ggc ggg ggo ggu goa gob goc gog goo gou gu- gua gub guc gug guo guu oaa oab oac oag oao oau ob- oba obb obc obg obo obu oc- oca ocb occ ocg oco ocu oga ogc ogg ogo oo- ooa oob ooc oog ooo ou- oua ouc ouo ua- uaa uab uac uag uao uau uba ubb ubc ubg ubo ubu uca ucb ucc ucg uco ucu uga ugb ugc ugg ugo ugu uoa uob uoc uog uoo uua uuc uug uuu