-er a-a a-b a-c aaa aab aac aae aak aan aap aar ab- aba abb abc abe abk abn abp abr ac- aca acb acc ace ack acn acp acr aea aeb aec aee aek aen aep aer aka akb akc ake akk akn akp akr an- ana anb anc ane ank ann anp anr ap- apa apb apc ape apk apn app apr ar- ara arb arc are ark arn arp arr b-p baa bab bac bae bak ban bap bar bba bbb bbc bbe bbk bbn bbp bbr bca bcb bcc bce bck bcn bcp bcr be- bea beb bec bee bek ben bep ber bka bkb bkc bke bkk bkn bkp bkr bna bnb bnc bne bnk bnn bnp bnr bpa bpb bpc bpe bpn bpp bpr bra brb bre brk brn brp brr c-- caa cab cac cae cak can cap car cba cbb cbc cbe cbk cbn cbp cbr cca ccb ccc cce cck ccn ccp ccr ce- cea ceb cec cee cek cen cep cer cka ckb ckc cn- cna cnb cnc cne cnn cnp cnr cpa cpb cpc cpe cpk cpn cpp cpr cra crb crc cre crk crn crp crr eaa eab eac eae eak ean eap ear eba ebb ebc ebe ebk ebn ebp ebr ec- eca ecb ecc ece eck ecn ecr eea eeb eec eee eek een eep eer eka ekb ekc eke ekp ekr en- ena enb enc ene enk enn enp enr ep- epa epb epc epe epn epp epr era erb erc ere erk ern erp err ka- kaa kab kac kae kak kan kap kar kba kbb kbc kbe kbk kbn kbp kbr kca kcb kcc kce kck kcn kcp kcr ke- kea keb kec kee kek ken kep ker kkb kkc kke kkk kkn kkp kkr kn- kna knc kne knk knn knp knr kpa kpc kpe kpk kpn kpp kpr kra krc krk krn krp krr naa nab nac nae nak nan nap nar nba nbb nbc nbe nbk nbn nbp nbr nca ncb ncc nce nck ncn ncp ncr ne- nea neb nec nee nek nen nep ner nka nkc nke nkk nkn nkp nkr nna nnb nnc nne nnk nnn nnp npa npb npc npe npn npp npr nra nrb nrc nre nrk nrn nrp nrr p-p paa pab pac pae pak pan pap par pba pbb pbc pbe pbk pbn pbp pbr pca pcb pcc pce pck pcn pcp pcr pea peb pec pee pek pen pep per pka pkb pkc pke pkn pkp pkr pn- pna pnb pnc pne pnk pnn pnp pnr ppa ppb ppc ppe ppk ppn ppp ppr pra prb prc pre prk prn prp prr ra- raa rab rac rae rak ran rap rar rba rbb rbc rbe rbk rbn rbp rbr rca rcb rcc rce rcn rcp rcr re- rea reb rec ree rek ren rep rer rkb rkc rke rkk rkp rna rnb rnc rnn rnp rnr rpa rpb rpc rpe rpk rpn rpp rpr rra rrb rrc rrk rrn rrp rrr