-er a-a a-c aaa aac aad aae aar aax ac- aca acc acd ace acr acx ad- ada adc add ade adr adx aea aec aed aee aer aex ar- ara arc ard are arr arx ax- axa axe axr axx c-- caa cac cad cae car cax cca ccc ccd cce ccr ccx cda cdc cdd cde cdr cdx ce- cea cec ced cee cer cex cra crc crd cre crr crx cxc cxr cxx daa dac dad dae dar dax dca dcc dcd dce dcr dcx dda ddc ddd dde ddr ddx de- dea dec ded dee der dex dra drc drd dre drr drx dxc dxd dxr dxx eaa eac ead eae ear eax ec- eca ecc ecd ece ecr ecx ed- eda edc edd ede edr edx eea eec eed eee eer eex era erc erd ere err ex- exa exc exd exe exr exx ra- raa rac rad rae rar rax rca rcc rcd rce rcr rcx rda rdc rdd rde rdr rdx re- rea rec red ree rer rex rra rrc rrd rrr rxr xaa xac xad xar xcd xcr xcx xda xdc xde xdr xed xee xer xex xrc xrd xrx xxx