-er a-a a-b a-c aaa aab aac aad aae aao aar aas aax ab- aba abb abc abd abe abo abr abs abx ac- aca acb acc acd ace aco acr acs acx ad- ada adb adc add ade ado adr ads adx aea aeb aec aed aee aeo aer aes aex aoa aob aoc aod aoe aoo aor aos aox ar- ara arb arc ard are aro arr ars arx as- asa asb asc asd ase aso asr ass asx ax- axa axe axo axr axs axx baa bab bac bad bae bao bar bas bax bba bbb bbc bbd bbe bbo bbr bbs bbx bca bcb bcc bcd bce bco bcr bcs bcx bda bdb bdc bdd bde bdo bdr bds bdx be- bea beb bec bed bee beo ber bes bex boa bob boc bod boe boo bor bos box bra brb brd bre bro brr brs brx bsa bsb bsc bsd bse bso bsr bss bsx bxb bxd bxo bxx c-- caa cab cac cad cae cao car cas cax cba cbb cbc cbd cbe cbo cbr cbs cbx cca ccb ccc ccd cce cco ccr ccs ccx cda cdb cdc cdd cde cdo cdr cds cdx ce- cea ceb cec ced cee ceo cer ces cex co- coa cob coc cod coe coo cor cos cox cra crb crc crd cre cro crr crs crx csa csb csc csd cse cso csr css csx cxc cxo cxr cxs cxx daa dab dac dad dae dao dar das dax dba dbb dbc dbd dbe dbo dbr dbs dbx dca dcb dcc dcd dce dco dcr dcs dcx dda ddb ddc ddd dde ddo ddr dds ddx de- dea deb dec ded dee deo der des dex doa dob doc dod doe doo dor dos dox dra drb drc drd dre dro drr drs drx dsa dsb dsc dsd dse dso dsr dss dsx dxc dxd dxo dxr dxs dxx eaa eab eac ead eae eao ear eas eax eba ebb ebc ebd ebe ebo ebr ebs ebx ec- eca ecb ecc ecd ece eco ecr ecs ecx ed- eda edb edc edd ede edo edr eds edx eea eeb eec eed eee eeo eer ees eex eo- eoa eob eoc eod eoe eoo eor eos era erb erc erd ere ero err ers es- esa esb esc esd ese eso esr ess esx ex- exa exc exd exe exo exr exs exx oaa oab oac oad oae oao oar oas oax ob- oba obb obc obd obe obo obr obs obx oc- oca ocb occ ocd oco ocr ocs ocx oda odb odc odd ode odo odr ods oea oeb oec oed oee oeo oer oes oex oo- ooa oob ooc ood ooo oor oos oox or- ora orb orc ord ore oro orr ors orx os- osa osb osc osd ose oso osr oss osx ox- oxa oxb oxc oxo oxx ra- raa rab rac rad rae rao rar ras rax rba rbb rbc rbd rbe rbo rbr rbs rbx rca rcb rcc rcd rce rco rcr rcs rcx rda rdb rdc rdd rde rdo rdr rds rdx re- rea reb rec red ree reo rer res rex roa rob roc rod roe roo ror ros rox rra rrb rrc rrd rrr rrs rsa rsb rsc rsd rse rso rsr rss rsx rxr rxs saa sab sac sad sae sao sar sas sax sba sbb sbc sbd sbe sbo sbr sbs sbx sca scb scc scd sce sco scr scs scx sda sdb sdc sdd sde sdo sdr sds se- sea seb sec sed see seo ser ses sex soa sob soc sod soe soo sor sos sox sr- sra srb src srd sre sro srr srs srx ss- ssa ssb ssc ssd sse sso ssr sss ssx sxc sxs xaa xac xad xar xas xbc xbe xbr xbx xcb xcd xcr xcx xda xdb xdc xde xdr xds xed xee xer xes xex xoa xoc xod xoo xor xos xox xrc xrd xrx xsa xsb xsc xss xxo xxx