-er a-a a-b a-c aaa aab aac aae aak aap aar aas ab- aba abb abc abe abk abp abr abs ac- aca acb acc ace ack acp acr acs aea aeb aec aee aek aep aer aes aka akb akc ake akk akp akr aks ap- apa apb apc ape apk app apr aps ar- ara arb arc are ark arp arr ars as- asa asb asc ase ask asp asr ass b-p baa bab bac bae bak bap bar bas bba bbb bbc bbe bbk bbp bbr bbs bca bcb bcc bce bck bcp bcr bcs be- bea beb bec bee bek bep ber bes bka bkb bkc bke bkk bkp bkr bks bpa bpb bpc bpe bpp bpr bps bra brb bre brk brp brr brs bsa bsb bsc bse bsk bsp bsr bss c-- caa cab cac cae cak cap car cas cba cbb cbc cbe cbk cbp cbr cbs cca ccb ccc cce cck ccp ccr ccs ce- cea ceb cec cee cek cep cer ces cka ckb ckc cks cpa cpb cpc cpe cpk cpp cpr cps cra crb crc cre crk crp crr crs csa csb csc cse csk csp csr css eaa eab eac eae eak eap ear eas eba ebb ebc ebe ebk ebp ebr ebs ec- eca ecb ecc ece eck ecr ecs eea eeb eec eee eek eep eer ees eka ekb ekc eke ekp ekr eks ep- epa epb epc epe epp epr eps era erb erc ere erk erp err ers es- esa esb esc ese esk esp esr ess ka- kaa kab kac kae kak kap kar kas kba kbb kbc kbe kbk kbp kbr kbs kca kcb kcc kce kck kcp kcr kcs ke- kea keb kec kee kek kep ker kes kkb kkc kke kkk kkp kkr kks kpa kpc kpe kpk kpp kpr kps kra krc krk krp krr krs ksa ksb ksc kse ksk ksp ksr kss p-p paa pab pac pae pak pap par pas pba pbb pbc pbe pbk pbp pbr pbs pca pcb pcc pce pck pcp pcr pcs pea peb pec pee pek pep per pes pka pkb pkc pke pkp pkr pks ppa ppb ppc ppe ppk ppp ppr pps pra prb prc pre prk prp prr prs ps- psa psb psc pse psk psp psr pss ra- raa rab rac rae rak rap rar ras rba rbb rbc rbe rbk rbp rbr rbs rca rcb rcc rce rcp rcr rcs re- rea reb rec ree rek rep rer res rkb rkc rke rkk rkp rks rpa rpb rpc rpe rpk rpp rpr rps rra rrb rrc rrk rrp rrr rrs rsa rsb rsc rse rsk rsp rsr rss saa sab sac sae sak sap sar sas sba sbb sbc sbe sbk sbp sbr sbs sca scb scc sce sck scp scr scs se- sea seb sec see sek sep ser ses sk- ska skb skc ske skk skp skr sks spa spb spc spe spk spp spr sps sr- sra srb src sre srk srp srr srs ss- ssa ssb ssc sse ssk ssp ssr sss