-er -ic a-a a-b a-c a-i aaa aab aac aae aai aar ab- aba abb abc abe abi abr ac- aca acb acc ace aci acr aea aeb aec aee aei aer ai- aia aib aic aie aii air ar- ara arb arc are ari arr baa bab bac bae bai bar bba bbb bbc bbe bbi bbr bca bcb bcc bce bci bcr be- bea beb bec bee bei ber bi- bia bib bic bie bii bir bra brb bre bri brr c-- caa cab cac cae cai car cba cbb cbc cbe cbi cbr cca ccb ccc cce cci ccr ce- cea ceb cec cee cei cer ci- cia cib cic cie cii cir cra crb crc cre cri crr eaa eab eac eae eai ear eba ebb ebc ebe ebi ebr ec- eca ecb ecc ece eci ecr eea eeb eec eee eer eia eib eic eie eii eir era erb erc ere eri err ia- iaa iab iac iae iai iar iba ibb ibc ibe ibi ibr ica icb icc ice ici icr ie- iea iec iee iei ier iia iib iic iie iii iir ir- ira irb irc ire iri irr ra- raa rab rac rae rai rar rba rbb rbc rbe rbi rbr rca rcb rcc rce rci rcr re- rea reb rec ree rei rer ria rib ric rie rii rir rra rrb rrc rri rrr