-er a-a a-b a-c aaa aab aac aae aam aao aar aax ab- aba abb abc abe abm abo abr abx ac- aca acb acc ace acm aco acr acx aea aeb aec aee aem aeo aer aex ama amb amc ame amm amo amr amx aoa aob aoc aoe aom aoo aor aox ar- ara arb arc are arm aro arr arx ax- axa axe axm axo axr axx baa bab bac bae bam bao bar bax bba bbb bbc bbe bbm bbo bbr bbx bca bcb bcc bce bcm bco bcr bcx be- bea beb bec bee bem beo ber bex bma bmb bmc bme bmm bmo bmr bmx boa bob boc boe bom boo bor box bra brb bre brm bro brr brx bxb bxm bxo bxx c-- caa cab cac cae cam cao car cax cba cbb cbc cbe cbm cbo cbr cbx cca ccb ccc cce ccm cco ccr ccx ce- cea ceb cec cee cem ceo cer cex cma cmb cmc cme cmm cmo cmr cmx co- coa cob coc coe com coo cor cox cra crb crc cre crm cro crr crx cxc cxo cxr cxx eaa eab eac eae eam eao ear eax eba ebb ebc ebe ebm ebo ebr ebx ec- eca ecb ecc ece ecm eco ecr ecx eea eeb eec eee eem eeo eer eex em- ema emb emc eme emm emo emr emx eo- eoa eob eoc eoe eom eoo eor era erb erc ere erm ero err ex- exa exc exe exo exr exx m-o m-r maa mab mac mae mam mao mar max mba mbb mbc mbe mbm mbo mbr mbx mc- mca mcb mcc mce mcm mco mcr mcx mea meb mec mee mem meo mer mex mma mmb mmc mme mmm mmo mmr mmx moa mob moc moe mom moo mor mox mra mrb mrc mre mrm mro mrr mrx mxa mxc mxr oaa oab oac oae oam oao oar oax ob- oba obb obc obe obm obo obr obx oc- oca ocb occ ocm oco ocr ocx oea oeb oec oee oem oeo oer oex om- oma omb omc ome omm omo omr omx oo- ooa oob ooc oom ooo oor oox or- ora orb orc ore orm oro orr orx ox- oxa oxb oxc oxo oxx ra- raa rab rac rae ram rao rar rax rba rbb rbc rbe rbm rbo rbr rbx rca rcb rcc rce rcm rco rcr rcx re- rea reb rec ree rem reo rer rex rma rmb rmc rme rmm rmo rmr rmx roa rob roc roe rom roo ror rox rra rrb rrc rrm rrr rxr xaa xac xam xar xbc xbe xbr xbx xcb xcr xcx xee xem xer xex xma xmc xmm xmo xmr xmx xoa xoc xom xoo xor xox xrc xrx xxo xxx