-er bbb bbc bbe bbm bbo bbr bbx bcb bcc bce bcm bco bcr bcx be- beb bec bee bem beo ber bex bmb bmc bme bmm bmo bmr bmx bob boc boe bom boo bor box brb bre brm bro brr brx bxb bxm bxo bxx c-- cbb cbc cbe cbm cbo cbr cbx ccb ccc cce ccm cco ccr ccx ce- ceb cec cee cem ceo cer cex cmb cmc cme cmm cmo cmr cmx co- cob coc coe com coo cor cox crb crc cre crm cro crr crx cxc cxo cxr cxx ebb ebc ebe ebm ebo ebr ebx ec- ecb ecc ece ecm eco ecr ecx eeb eec eee eem eeo eer eex em- emb emc eme emm emo emr emx eo- eob eoc eoe eom eoo eor erb erc ere erm ero err ex- exc exe exo exr exx m-o m-r mbb mbc mbe mbm mbo mbr mbx mc- mcb mcc mce mcm mco mcr mcx meb mec mee mem meo mer mex mmb mmc mme mmm mmo mmr mmx mob moc moe mom moo mor mox mrb mrc mre mrm mro mrr mrx mxc mxr ob- obb obc obe obm obo obr obx oc- ocb occ ocm oco ocr ocx oeb oec oee oem oeo oer oex om- omb omc ome omm omo omr omx oo- oob ooc oom ooo oor oox or- orb orc ore orm oro orr orx ox- oxb oxc oxo oxx rbb rbc rbe rbm rbo rbr rbx rcb rcc rce rcm rco rcr rcx re- reb rec ree rem reo rer rex rmb rmc rme rmm rmo rmr rmx rob roc roe rom roo ror rox rrb rrc rrm rrr rxr xbc xbe xbr xbx xcb xcr xcx xee xem xer xex xmc xmm xmo xmr xmx xoc xom xoo xor xox xrc xrx xxo xxx