a-a a-c aaa aac aan aar aax ac- aca acc acn acr acx an- ana anc ann anr anx ar- ara arc arn arr arx ax- axa axn axr axx c-- caa cac can car cax cca ccc ccn ccr ccx cn- cna cnc cnn cnr cnx cra crc crn crr crx cxc cxr cxx naa nac nan nar nax nca ncc ncn ncr ncx nna nnc nnn nra nrc nrn nrr nrx nxc ra- raa rac ran rar rax rca rcc rcn rcr rcx rna rnc rnn rnr rra rrc rrn rrr rxr xaa xac xan xar xcr xcx xna xnc xrc xrx xxx