-er a-a a-b a-c aaa aab aac aae aap aar aas ab- aba abb abc abe abp abr abs ac- aca acb acc ace acp acr acs aea aeb aec aee aep aer aes ap- apa apb apc ape app apr aps ar- ara arb arc are arp arr ars as- asa asb asc ase asp asr ass b-p baa bab bac bae bap bar bas bba bbb bbc bbe bbp bbr bbs bca bcb bcc bce bcp bcr bcs be- bea beb bec bee bep ber bes bpa bpb bpc bpe bpp bpr bps bra brb bre brp brr brs bsa bsb bsc bse bsp bsr bss c-- caa cab cac cae cap car cas cba cbb cbc cbe cbp cbr cbs cca ccb ccc cce ccp ccr ccs ce- cea ceb cec cee cep cer ces cpa cpb cpc cpe cpp cpr cps cra crb crc cre crp crr crs csa csb csc cse csp csr css eaa eab eac eae eap ear eas eba ebb ebc ebe ebp ebr ebs ec- eca ecb ecc ece ecr ecs eea eeb eec eee eep eer ees ep- epa epb epc epe epp epr eps era erb erc ere erp err ers es- esa esb esc ese esp esr ess p-p paa pab pac pae pap par pas pba pbb pbc pbe pbp pbr pbs pca pcb pcc pce pcp pcr pcs pea peb pec pee pep per pes ppa ppb ppc ppe ppp ppr pps pra prb prc pre prp prr prs ps- psa psb psc pse psp psr pss ra- raa rab rac rae rap rar ras rba rbb rbc rbe rbp rbr rbs rca rcb rcc rce rcp rcr rcs re- rea reb rec ree rep rer res rpa rpb rpc rpe rpp rpr rps rra rrb rrc rrp rrr rrs rsa rsb rsc rse rsp rsr rss saa sab sac sae sap sar sas sba sbb sbc sbe sbp sbr sbs sca scb scc sce scp scr scs se- sea seb sec see sep ser ses spa spb spc spe spp spr sps sr- sra srb src sre srp srr srs ss- ssa ssb ssc sse ssp ssr sss