-er a-a a-b a-c aaa aab aac aae aap aar ab- aba abb abc abe abp abr ac- aca acb acc ace acp acr aea aeb aec aee aep aer ap- apa apb apc ape app apr ar- ara arb arc are arp arr b-p baa bab bac bae bap bar bba bbb bbc bbe bbp bbr bca bcb bcc bce bcp bcr be- bea beb bec bee bep ber bpa bpb bpc bpe bpp bpr bra brb bre brp brr c-- caa cab cac cae cap car cba cbb cbc cbe cbp cbr cca ccb ccc cce ccp ccr ce- cea ceb cec cee cep cer cpa cpb cpc cpe cpp cpr cra crb crc cre crp crr eaa eab eac eae eap ear eba ebb ebc ebe ebp ebr ec- eca ecb ecc ece ecr eea eeb eec eee eep eer ep- epa epb epc epe epp epr era erb erc ere erp err p-p paa pab pac pae pap par pba pbb pbc pbe pbp pbr pca pcb pcc pce pcp pcr pea peb pec pee pep per ppa ppb ppc ppe ppp ppr pra prb prc pre prp prr ra- raa rab rac rae rap rar rba rbb rbc rbe rbp rbr rca rcb rcc rce rcp rcr re- rea reb rec ree rep rer rpa rpb rpc rpe rpp rpr rra rrb rrc rrp rrr