-er a-a a-b a-c aaa aab aac aae aak aap aar ab- aba abb abc abe abk abp abr ac- aca acb acc ace ack acp acr aea aeb aec aee aek aep aer aka akb akc ake akk akp akr ap- apa apb apc ape apk app apr ar- ara arb arc are ark arp arr b-p baa bab bac bae bak bap bar bba bbb bbc bbe bbk bbp bbr bca bcb bcc bce bck bcp bcr be- bea beb bec bee bek bep ber bka bkb bkc bke bkk bkp bkr bpa bpb bpc bpe bpp bpr bra brb bre brk brp brr c-- caa cab cac cae cak cap car cba cbb cbc cbe cbk cbp cbr cca ccb ccc cce cck ccp ccr ce- cea ceb cec cee cek cep cer cka ckb ckc cpa cpb cpc cpe cpk cpp cpr cra crb crc cre crk crp crr eaa eab eac eae eak eap ear eba ebb ebc ebe ebk ebp ebr ec- eca ecb ecc ece eck ecr eea eeb eec eee eek eep eer eka ekb ekc eke ekp ekr ep- epa epb epc epe epp epr era erb erc ere erk erp err ka- kaa kab kac kae kak kap kar kba kbb kbc kbe kbk kbp kbr kca kcb kcc kce kck kcp kcr ke- kea keb kec kee kek kep ker kkb kkc kke kkk kkp kkr kpa kpc kpe kpk kpp kpr kra krc krk krp krr p-p paa pab pac pae pak pap par pba pbb pbc pbe pbk pbp pbr pca pcb pcc pce pck pcp pcr pea peb pec pee pek pep per pka pkb pkc pke pkp pkr ppa ppb ppc ppe ppk ppp ppr pra prb prc pre prk prp prr ra- raa rab rac rae rak rap rar rba rbb rbc rbe rbk rbp rbr rca rcb rcc rce rcp rcr re- rea reb rec ree rek rep rer rkb rkc rke rkk rkp rpa rpb rpc rpe rpk rpp rpr rra rrb rrc rrk rrp rrr