-er -ic b-u bbb bbc bbe bbi bbr bbs bbu bcb bcc bce bci bcr bcs bcu be- beb bec bee bei ber bes beu bi- bib bic bie bii bir bis biu brb bre bri brr brs bru bsb bsc bse bsi bsr bss bsu bub buc bue bui bur bus buu c-- cbb cbc cbe cbi cbr cbs cbu ccb ccc cce cci ccr ccs ccu ce- ceb cec cee cei cer ces ceu ci- cib cic cie cii cir cis ciu crb crc cre cri crr crs cru csb csc cse csi csr css csu cub cuc cue cui cur cus cuu ebb ebc ebe ebi ebr ebs ebu ec- ecb ecc ece eci ecr ecs ecu eeb eec eee eer ees eib eic eie eii eir eis eiu erb erc ere eri err ers eru es- esb esc ese esi esr ess esu eu- eub euc eue eui eur eus ibb ibc ibe ibi ibr ibs ibu icb icc ice ici icr ics icu ie- iec iee iei ier ies iib iic iie iii iir iis iiu ir- irb irc ire iri irr irs iru is- isb isc ise isi isr iss isu iu- iub iuc iue iui iur ius rbb rbc rbe rbi rbr rbs rbu rcb rcc rce rci rcr rcs rcu re- reb rec ree rei rer res reu rib ric rie rii rir ris rrb rrc rri rrr rrs rru rsb rsc rse rsi rsr rss rsu rub ruc rue rui rur rus ruu sbb sbc sbe sbi sbr sbs sbu scb scc sce sci scr scs scu se- seb sec see sei ser ses seu sib sic sie sii sir sis siu sr- srb src sre sri srr srs ss- ssb ssc sse ssi ssr sss ssu sub suc sue sui sur sus suu ubb ubc ube ubi ubr ubs ubu ucb ucc uce uci ucr ucs ucu ueb uec uee uei uer ues uib uic uie uii uir uis uiu ur- urb urc ure uri urr urs uru usb usc use usi usr uss usu uuc uue uur uus uuu