-ic a-a a-b a-c a-i aaa aab aac aai aak aas ab- aba abb abc abi abk abs ac- aca acb acc aci ack acs ai- aia aib aic aii aik ais aka akb akc aki akk aks as- asa asb asc asi ask ass baa bab bac bai bak bas bba bbb bbc bbi bbk bbs bca bcb bcc bci bck bcs bi- bia bib bic bii bik bis bka bkb bkc bkk bks bsa bsb bsc bsi bsk bss c-- caa cab cac cai cak cas cba cbb cbc cbi cbk cbs cca ccb ccc cci cck ccs ci- cia cib cic cii cik cis cka ckb ckc cki cks csa csb csc csi csk css ia- iaa iab iac iai ias iba ibb ibc ibi ibk ibs ica icb icc ici ick ics iia iib iic iii iis ika ikb ikc iki ikk iks is- isa isb isc isi isk iss ka- kaa kab kac kai kak kas kba kbb kbc kbi kbk kbs kca kcb kcc kci kck kcs kia kib kic kii kik kis kkb kkc kki kkk kks ksa ksb ksc ksi ksk kss saa sab sac sai sak sas sba sbb sbc sbi sbk sbs sca scb scc sci sck scs sia sib sic sii sik sis sk- ska skb skc ski skk sks ss- ssa ssb ssc ssi ssk sss