a-a a-t aaa aar aas aat aax ar- ara arr ars art arx as- asa asr ass ast asx at- ata atr ats att atx ax- axa axr axs axt axx ra- raa rar ras rat rax rra rrr rrs rrt rsa rsr rss rst rsx rta rtr rts rtt rtx rxr rxs saa sar sas sat sax sr- sra srr srs srt srx ss- ssa ssr sss sst ssx sta str sts stt stx sxs sxt t-x taa tar tas tat tax tra trr trs trt trx tsa tsr tss tst tsx tta ttr tts ttt ttx txs txt xaa xar xas xat xrt xrx xsa xss xst xtr xts xtx xxx