bbb bbc bbs bbt bby bcb bcc bcs bct bcy bsb bsc bss bst bsy btb btc bts btt bty by- byc bys byt c-- cbb cbc cbs cbt cby ccb ccc ccs cct csb csc css cst csy ctb ctc cts ctt cty cyb cyc cys cyt sbb sbc sbs sbt sby scb scc scs sct ss- ssb ssc sss sst stb stc sts stt sty sy- syb syc sys syt tbb tbc tbs tbt tcb tcc tcs tct tsb tsc tss tst tsy ttb ttc tts ttt tty tyc tys tyt ybc ybs yby ycc ycs ycy ysb ysc yss yst ysy ytc yts ytt yyb yyc yys yyt yyy