-er a-a a-b a-c aaa aab aac aae aao aar aas aau aax ab- aba abb abc abe abo abr abs abu abx ac- aca acb acc ace aco acr acs acu acx aea aeb aec aee aeo aer aes aeu aex aoa aob aoc aoe aoo aor aos aou aox ar- ara arb arc are aro arr ars aru arx as- asa asb asc ase aso asr ass asu asx au- aua aub auc aue auo aur aus aux ax- axa axe axo axr axs axx b-u baa bab bac bae bao bar bas bau bax bba bbb bbc bbe bbo bbr bbs bbu bbx bca bcb bcc bce bco bcr bcs bcu bcx be- bea beb bec bee beo ber bes beu bex boa bob boc boe boo bor bos bou box bra brb bre bro brr brs bru brx bsa bsb bsc bse bso bsr bss bsu bsx bua bub buc bue buo bur bus buu bux bxb bxo bxx c-- caa cab cac cae cao car cas cau cax cba cbb cbc cbe cbo cbr cbs cbu cbx cca ccb ccc cce cco ccr ccs ccu ccx ce- cea ceb cec cee ceo cer ces ceu cex co- coa cob coc coe coo cor cos cou cox cra crb crc cre cro crr crs cru crx csa csb csc cse cso csr css csu csx cua cub cuc cue cuo cur cus cuu cxc cxo cxr cxs cxx eaa eab eac eae eao ear eas eau eax eba ebb ebc ebe ebo ebr ebs ebu ebx ec- eca ecb ecc ece eco ecr ecs ecu ecx eea eeb eec eee eeo eer ees eex eo- eoa eob eoc eoe eoo eor eos eou era erb erc ere ero err ers eru es- esa esb esc ese eso esr ess esu esx eu- eua eub euc eue eur eus eux ex- exa exc exe exo exr exs exu exx oaa oab oac oae oao oar oas oau oax ob- oba obb obc obe obo obr obs obu obx oc- oca ocb occ oco ocr ocs ocu ocx oea oeb oec oee oeo oer oes oex oo- ooa oob ooc ooo oor oos oox or- ora orb orc ore oro orr ors oru orx os- osa osb osc ose oso osr oss osu osx ou- oua ouc oue ouo our ous ox- oxa oxb oxc oxo oxx ra- raa rab rac rae rao rar ras rau rax rba rbb rbc rbe rbo rbr rbs rbu rbx rca rcb rcc rce rco rcr rcs rcu rcx re- rea reb rec ree reo rer res reu rex roa rob roc roe roo ror ros rou rox rra rrb rrc rrr rrs rru rsa rsb rsc rse rso rsr rss rsu rsx rua rub ruc rue ruo rur rus ruu rux rxr rxs saa sab sac sae sao sar sas sau sax sba sbb sbc sbe sbo sbr sbs sbu sbx sca scb scc sce sco scr scs scu scx se- sea seb sec see seo ser ses seu sex soa sob soc soe soo sor sos sou sox sr- sra srb src sre sro srr srs srx ss- ssa ssb ssc sse sso ssr sss ssu ssx sua sub suc sue suo sur sus suu sux sxc sxs sxu ua- uaa uab uac uae uao uar uas uau uba ubb ubc ube ubo ubr ubs ubu ubx uca ucb ucc uce uco ucr ucs ucu uea ueb uec uee uer ues uoa uob uoc uoe uoo uor uos uox ur- ura urb urc ure uro urr urs uru urx usa usb usc use uso usr uss usu usx uua uuc uue uur uus uuu uxb uxc uxo uxr uxu xaa xac xar xas xau xbc xbe xbr xbx xcb xcr xcx xee xer xes xeu xex xoa xoc xoo xor xos xox xrc xrx xsa xsb xsc xss xue xus xxo xxx