c-- ccc ccd cck cco ccr cdc cdd cdk cdo cdr cdy ckc ckd cko cky co- coc cod cok coo cor coy crc crd crk cro crr cry cyc cyd cyk cyo cyr dcc dcd dck dco dcr ddc ddd ddk ddo ddr ddy dkc dkk dko dkr doc dod dok doo dor doy drc drd drk dro drr dry dy- dyc dyd dyk dyo dyr dyy kcc kcd kck kcr kdc kdk kdo kdr kdy kkc kkk kkr kky koc kod kok koo kor koy krc krd krk kro krr kry kyc kyd kyo kyr oc- occ ocd ock oco ocr odc odd odo odr okc okd okk oko okr oo- ooc ood ook ooo oor or- orc ord ork oro orr ory oyd oyo rcc rcd rco rcr rdc rdd rdo rdr rdy rkc rkk rko rky roc rod rok roo ror roy rrc rrd rrk rrr ry- ryc ryd ryk ryo ryr ryy ycc ycd yco ycy ydo ydy ykk yoc yod yok yoo yor yoy yrc yro yyc yyy