-er -ic a-a a-b a-c a-i aaa aab aac aae aai aak aar ab- aba abb abc abe abi abk abr ac- aca acb acc ace aci ack acr aea aeb aec aee aei aek aer ai- aia aib aic aie aii aik air aka akb akc ake aki akk akr ar- ara arb arc are ari ark arr baa bab bac bae bai bak bar bba bbb bbc bbe bbi bbk bbr bca bcb bcc bce bci bck bcr be- bea beb bec bee bei bek ber bi- bia bib bic bie bii bik bir bka bkb bkc bke bkk bkr bra brb bre bri brk brr c-- caa cab cac cae cai cak car cba cbb cbc cbe cbi cbk cbr cca ccb ccc cce cci cck ccr ce- cea ceb cec cee cei cek cer ci- cia cib cic cie cii cik cir cka ckb ckc cki cra crb crc cre cri crk crr eaa eab eac eae eai eak ear eba ebb ebc ebe ebi ebk ebr ec- eca ecb ecc ece eci eck ecr eea eeb eec eee eek eer eia eib eic eie eii eik eir eka ekb ekc eke eki ekr era erb erc ere eri erk err ia- iaa iab iac iae iai iar iba ibb ibc ibe ibi ibk ibr ica icb icc ice ici ick icr ie- iea iec iee iei iek ier iia iib iic iie iii iir ika ikb ikc ike iki ikk ikr ir- ira irb irc ire iri irk irr ka- kaa kab kac kae kai kak kar kba kbb kbc kbe kbi kbk kbr kca kcb kcc kce kci kck kcr ke- kea keb kec kee kei kek ker kia kib kic kie kii kik kir kkb kkc kke kki kkk kkr kra krc kri krk krr ra- raa rab rac rae rai rak rar rba rbb rbc rbe rbi rbk rbr rca rcb rcc rce rci rcr re- rea reb rec ree rei rek rer ria rib ric rie rii rik rir rkb rkc rke rkk rra rrb rrc rri rrk rrr