a-a a-c aaa aac aao aar aax aay ac- aca acc aco acr acx acy aoa aoc aoo aor aox ar- ara arc aro arr arx ary ax- axa axo axr axx ay- aya ayc ayo ayr ayx c-- caa cac cao car cax cay cca ccc cco ccr ccx co- coa coc coo cor cox coy cra crc cro crr crx cry cxc cxo cxr cxx cya cyc cyo cyr oaa oac oao oar oax oc- oca occ oco ocr ocx oo- ooa ooc ooo oor oox or- ora orc oro orr orx ory ox- oxa oxc oxo oxx oxy oya oyo ra- raa rac rao rar rax ray rca rcc rco rcr rcx roa roc roo ror rox roy rra rrc rrr rxr ry- rya ryc ryo ryr ryy xaa xac xar xcr xcx xoa xoc xoo xor xox xrc xrx xry xxo xxx xxy xyr xyy yaa yac yao yar yax yay yca ycc yco ycy yoc yoo yor yox yoy yra yrc yro yxa yxy yyc yyy