a-a a-b a-t a-z aaa aab aar aas aat aaz ab- aba abb abr abs abt abz ar- ara arb arr ars art arz as- asa asb asr ass ast asz at- ata atb atr ats att atz az- aza azb azs azt azz baa bab bar bas bat baz bba bbb bbr bbs bbt bra brb brr brs brt brz bsa bsb bsr bss bst bta btb btr bts btt btz bza bzr bzs bzz ra- raa rab rar ras rat raz rba rbb rbr rbs rbt rra rrb rrr rrs rrt rsa rsb rsr rss rst rta rtb rtr rts rtt rtz rza rzb saa sab sar sas sat saz sba sbb sbr sbs sbt sr- sra srb srr srs srt ss- ssa ssb ssr sss sst ssz sta stb str sts stt stz sza szr taa tab tar tas tat taz tba tbb tbr tbs tbt tbz tra trb trr trs trt trz tsa tsb tsr tss tst tta ttb ttr tts ttt tza tzs zaa zab zar zas zat zaz zbb zbr zbs zbt zrs zsa zst zsz zta ztr zzr zzs zzt zzz