a-a a-c aaa aac aao aar aax ac- aca acc aco acr acx aoa aoc aoo aor aox ar- ara arc aro arr arx ax- axa axo axr axx c-- caa cac cao car cax cca ccc cco ccr ccx co- coa coc coo cor cox cra crc cro crr crx cxc cxo cxr cxx oaa oac oao oar oax oc- oca occ oco ocr ocx oo- ooa ooc ooo oor oox or- ora orc oro orr orx ox- oxa oxc oxo oxx ra- raa rac rao rar rax rca rcc rco rcr rcx roa roc roo ror rox rra rrc rrr rxr xaa xac xar xcr xcx xoa xoc xoo xor xox xrc xrx xxo xxx