-er -ic b-p bbb bbc bbe bbi bbp bbr bcb bcc bce bci bcp bcr be- beb bec bee bei bep ber bi- bib bic bie bii bip bir bpb bpc bpe bpi bpp bpr brb bre bri brp brr c-- cbb cbc cbe cbi cbp cbr ccb ccc cce cci ccp ccr ce- ceb cec cee cei cep cer ci- cib cic cie cii cip cir cpb cpc cpe cpi cpp cpr crb crc cre cri crp crr ebb ebc ebe ebi ebp ebr ec- ecb ecc ece eci ecr eeb eec eee eep eer eib eic eie eii eip eir ep- epb epc epe epi epp epr erb erc ere eri erp err ibb ibc ibe ibi ibp ibr icb icc ice ici icp icr ie- iec iee iei iep ier iib iic iie iii iip iir ipb ipc ipe ipi ipp ipr ir- irb irc ire iri irp irr p-p pbb pbc pbe pbi pbp pbr pcb pcc pce pci pcp pcr peb pec pee pei pep per pib pic pie pii pip pir ppb ppc ppe ppi ppp ppr prb prc pre pri prp prr rbb rbc rbe rbi rbp rbr rcb rcc rce rci rcp rcr re- reb rec ree rei rep rer rib ric rie rii rip rir rpb rpc rpe rpi rpp rpr rrb rrc rri rrp rrr