a-a a-b a-c aaa aab aac aau aay ab- aba abb abc abu aby ac- aca acb acc acu acy au- aua aub auc ay- aya ayc ayu b-u baa bab bac bau bay bba bbb bbc bbu bby bca bcb bcc bcu bcy bua bub buc buu buy by- bya byc byu c-- caa cab cac cau cay cba cbb cbc cbu cby cca ccb ccc ccu cua cub cuc cuu cuy cya cyb cyc ua- uaa uab uac uau uay uba ubb ubc ubu uby uca ucb ucc ucu uua uuc uuu uyc uyu yaa yab yac yau yay ybc yby yca ycc ycu ycy yua yuu yuy yyb yyc yyu yyy