a-a a-b a-c aaa aab aac aao aau aay ab- aba abb abc abo abu aby ac- aca acb acc aco acu acy aoa aob aoc aoo aou au- aua aub auc auo ay- aya ayc ayo ayu b-u baa bab bac bao bau bay bba bbb bbc bbo bbu bby bca bcb bcc bco bcu bcy boa bob boc boo bou boy bua bub buc buo buu buy by- bya byc byo byu c-- caa cab cac cao cau cay cba cbb cbc cbo cbu cby cca ccb ccc cco ccu co- coa cob coc coo cou coy cua cub cuc cuo cuu cuy cya cyb cyc cyo oaa oab oac oao oau ob- oba obb obc obo obu oby oc- oca ocb occ oco ocu oo- ooa oob ooc ooo ou- oua ouc ouo oya oyo ua- uaa uab uac uao uau uay uba ubb ubc ubo ubu uby uca ucb ucc uco ucu uoa uob uoc uoo uua uuc uuu uyc uyo uyu yaa yab yac yao yau yay ybc yby yca ycc yco ycu ycy yob yoc yoo you yoy yua yuo yuu yuy yyb yyc yyu yyy