a-a a-b aaa aab aak aas aay ab- aba abb abk abs aby aka akb akk aks as- asa asb ask ass asy ay- aya ayk ays baa bab bak bas bay bba bbb bbk bbs bby bka bkb bkk bks bsa bsb bsk bss bsy by- bya byk bys ka- kaa kab kak kas kay kba kbb kbk kbs kkb kkk kks kky ksa ksb ksk kss kya kys saa sab sak sas say sba sbb sbk sbs sby sk- ska skb skk sks sky ss- ssa ssb ssk sss sy- sya syb syk sys yaa yab yak yas yay ybs yby yka ykk ysa ysb ysk yss ysy yyb yys yyy