-er a-a a-b a-c aaa aab aac aae aao aap aar aas ab- aba abb abc abe abo abp abr abs ac- aca acb acc ace aco acp acr acs aea aeb aec aee aeo aep aer aes aoa aob aoc aoe aoo aop aor aos ap- apa apb apc ape apo app apr aps ar- ara arb arc are aro arp arr ars as- asa asb asc ase aso asp asr ass b-p baa bab bac bae bao bap bar bas bba bbb bbc bbe bbo bbp bbr bbs bca bcb bcc bce bco bcp bcr bcs be- bea beb bec bee beo bep ber bes boa bob boc boe boo bop bor bos bpa bpb bpc bpe bpo bpp bpr bps bra brb bre bro brp brr brs bsa bsb bsc bse bso bsp bsr bss c-- caa cab cac cae cao cap car cas cba cbb cbc cbe cbo cbp cbr cbs cca ccb ccc cce cco ccp ccr ccs ce- cea ceb cec cee ceo cep cer ces co- coa cob coc coe coo cop cor cos cpa cpb cpc cpe cpo cpp cpr cps cra crb crc cre cro crp crr crs csa csb csc cse cso csp csr css eaa eab eac eae eao eap ear eas eba ebb ebc ebe ebo ebp ebr ebs ec- eca ecb ecc ece eco ecr ecs eea eeb eec eee eeo eep eer ees eo- eoa eob eoc eoe eoo eop eor eos ep- epa epb epc epe epo epp epr eps era erb erc ere ero erp err ers es- esa esb esc ese eso esp esr ess oaa oab oac oae oao oap oar oas ob- oba obb obc obe obo obp obr obs oc- oca ocb occ oco ocp ocr ocs oea oeb oec oee oeo oep oer oes oo- ooa oob ooc ooo oop oor oos op- opa opb opc ope opo opp opr ops or- ora orb orc ore oro orp orr ors os- osa osb osc ose oso osp osr oss p-p paa pab pac pae pao pap par pas pba pbb pbc pbe pbo pbp pbr pbs pca pcb pcc pce pco pcp pcr pcs pea peb pec pee peo pep per pes poa pob poc poe poo pop por pos ppa ppb ppc ppe ppo ppp ppr pps pra prb prc pre pro prp prr prs ps- psa psb psc pse pso psp psr pss ra- raa rab rac rae rao rap rar ras rba rbb rbc rbe rbo rbp rbr rbs rca rcb rcc rce rco rcp rcr rcs re- rea reb rec ree reo rep rer res roa rob roc roe roo rop ror ros rpa rpb rpc rpe rpo rpp rpr rps rra rrb rrc rrp rrr rrs rsa rsb rsc rse rso rsp rsr rss saa sab sac sae sao sap sar sas sba sbb sbc sbe sbo sbp sbr sbs sca scb scc sce sco scp scr scs se- sea seb sec see seo sep ser ses soa sob soc soe soo sop sor sos spa spb spc spe spo spp spr sps sr- sra srb src sre sro srp srr srs ss- ssa ssb ssc sse sso ssp ssr sss