c-- ccc ccr ccs cct crc crr crs crt cry csc csr css cst csy ctc ctr cts ctt cty cyc cyr cys cyt rcc rcr rcs rct rrc rrr rrs rrt rsc rsr rss rst rtc rtr rts rtt rty ry- ryc ryr rys ryy scc scr scs sct sr- src srr srs srt sry ss- ssc ssr sss sst stc str sts stt sty sy- syc syr sys syt tcc tcr tcs tct trc trr trs trt try tsc tsr tss tst tsy ttc ttr tts ttt tty tyc tyr tys tyt ycc ycs ycy yrc yrs yrt ysc ysr yss yst ysy ytc ytr yts ytt yyc yys yyt yyy