a-a a-b a-t aaa aab aar aas aat aay ab- aba abb abr abs abt aby ar- ara arb arr ars art ary as- asa asb asr ass ast asy at- ata atb atr ats att ay- aya ayr ays ayt baa bab bar bas bat bay bba bbb bbr bbs bbt bby bra brb brr brs brt bry bsa bsb bsr bss bst bsy bta btb btr bts btt bty by- bya byr bys byt ra- raa rab rar ras rat ray rba rbb rbr rbs rbt rra rrb rrr rrs rrt rsa rsb rsr rss rst rta rtb rtr rts rtt rty ry- rya ryr rys ryy saa sab sar sas sat say sba sbb sbr sbs sbt sby sr- sra srb srr srs srt sry ss- ssa ssb ssr sss sst sta stb str sts stt sty sy- sya syb syr sys syt taa tab tar tas tat tay tba tbb tbr tbs tbt tra trb trr trs trt try tsa tsb tsr tss tst tsy tta ttb ttr tts ttt tty tya tyr tys tyt yaa yab yar yas yat yay ybr ybs yby yra yrs yrt ysa ysb ysr yss yst ysy yta ytr yts ytt yyb yys yyt yyy