-er a-a a-b a-c aaa aab aac aae aar aas aau aax ab- aba abb abc abe abr abs abu abx ac- aca acb acc ace acr acs acu acx aea aeb aec aee aer aes aeu aex ar- ara arb arc are arr ars aru arx as- asa asb asc ase asr ass asu asx au- aua aub auc aue aur aus aux ax- axa axe axr axs axx b-u baa bab bac bae bar bas bau bax bba bbb bbc bbe bbr bbs bbu bbx bca bcb bcc bce bcr bcs bcu bcx be- bea beb bec bee ber bes beu bex bra brb bre brr brs bru brx bsa bsb bsc bse bsr bss bsu bsx bua bub buc bue bur bus buu bux bxb bxx c-- caa cab cac cae car cas cau cax cba cbb cbc cbe cbr cbs cbu cbx cca ccb ccc cce ccr ccs ccu ccx ce- cea ceb cec cee cer ces ceu cex cra crb crc cre crr crs cru crx csa csb csc cse csr css csu csx cua cub cuc cue cur cus cuu cxc cxr cxs cxx eaa eab eac eae ear eas eau eax eba ebb ebc ebe ebr ebs ebu ebx ec- eca ecb ecc ece ecr ecs ecu ecx eea eeb eec eee eer ees eex era erb erc ere err ers eru es- esa esb esc ese esr ess esu esx eu- eua eub euc eue eur eus eux ex- exa exc exe exr exs exu exx ra- raa rab rac rae rar ras rau rax rba rbb rbc rbe rbr rbs rbu rbx rca rcb rcc rce rcr rcs rcu rcx re- rea reb rec ree rer res reu rex rra rrb rrc rrr rrs rru rsa rsb rsc rse rsr rss rsu rsx rua rub ruc rue rur rus ruu rux rxr rxs saa sab sac sae sar sas sau sax sba sbb sbc sbe sbr sbs sbu sbx sca scb scc sce scr scs scu scx se- sea seb sec see ser ses seu sex sr- sra srb src sre srr srs srx ss- ssa ssb ssc sse ssr sss ssu ssx sua sub suc sue sur sus suu sux sxc sxs sxu ua- uaa uab uac uae uar uas uau uba ubb ubc ube ubr ubs ubu ubx uca ucb ucc uce ucr ucs ucu uea ueb uec uee uer ues ur- ura urb urc ure urr urs uru urx usa usb usc use usr uss usu usx uua uuc uue uur uus uuu uxb uxc uxr uxu xaa xac xar xas xau xbc xbe xbr xbx xcb xcr xcx xee xer xes xeu xex xrc xrx xsa xsb xsc xss xue xus xxx