c-- ccc cco ccp ccr ccx co- coc coo cop cor cox cpc cpo cpp cpr cpx crc cro crp crr crx cxc cxo cxp cxr cxx oc- occ oco ocp ocr ocx oo- ooc ooo oop oor oox op- opc opo opp opr opx or- orc oro orp orr orx ox- oxc oxo oxx p-p pcc pco pcp pcr pcx poc poo pop por pox ppc ppo ppp ppr ppx prc pro prp prr prx pxc pxr rcc rco rcp rcr rcx roc roo rop ror rox rpc rpo rpp rpr rpx rrc rrp rrr rxp rxr xcp xcr xcx xoc xoo xop xor xox xpc xpo xpp xrc xrx xxo xxp xxx