-er bbb bbc bbe bbo bbr bbx bcb bcc bce bco bcr bcx be- beb bec bee beo ber bex bob boc boe boo bor box brb bre bro brr brx bxb bxo bxx c-- cbb cbc cbe cbo cbr cbx ccb ccc cce cco ccr ccx ce- ceb cec cee ceo cer cex co- cob coc coe coo cor cox crb crc cre cro crr crx cxc cxo cxr cxx ebb ebc ebe ebo ebr ebx ec- ecb ecc ece eco ecr ecx eeb eec eee eeo eer eex eo- eob eoc eoe eoo eor erb erc ere ero err ex- exc exe exo exr exx ob- obb obc obe obo obr obx oc- ocb occ oco ocr ocx oeb oec oee oeo oer oex oo- oob ooc ooo oor oox or- orb orc ore oro orr orx ox- oxb oxc oxo oxx rbb rbc rbe rbo rbr rbx rcb rcc rce rco rcr rcx re- reb rec ree reo rer rex rob roc roe roo ror rox rrb rrc rrr rxr xbc xbe xbr xbx xcb xcr xcx xee xer xex xoc xoo xor xox xrc xrx xxo xxx