-er b-p bbb bbc bbe bbf bbp bbr bcb bcc bce bcf bcp bcr be- beb bec bee bef bep ber bfb bfc bfe bff bfp bfr bpb bpc bpe bpf bpp bpr brb bre brf brp brr c-- cbb cbc cbe cbf cbp cbr ccb ccc cce ccf ccp ccr ce- ceb cec cee cef cep cer cfb cfc cfe cff cfp cfr cpb cpc cpe cpf cpp cpr crb crc cre crf crp crr ebb ebc ebe ebf ebp ebr ec- ecb ecc ece ecf ecr eeb eec eee eef eep eer ef- efb efc efe eff efp efr ep- epb epc epe epf epp epr erb erc ere erf erp err fbb fbc fbe fbf fbp fbr fcb fcc fce fcf fcp fcr feb fec fee fef fep fer ffc ffe fff ffp ffr fpb fpc fpe fpp fpr frb frc fre frf frp frr p-p pbb pbc pbe pbf pbp pbr pcb pcc pce pcf pcp pcr peb pec pee pef pep per pfb pfc pfe pff pfp pfr ppb ppc ppe ppf ppp ppr prb prc pre prf prp prr rbb rbc rbe rbf rbp rbr rcb rcc rce rcf rcp rcr re- reb rec ree ref rep rer rfb rfc rfe rff rfp rfr rpb rpc rpe rpf rpp rpr rrb rrc rrf rrp rrr