-ic a-a a-b a-c a-i aaa aab aac aai aas ab- aba abb abc abi abs ac- aca acb acc aci acs ai- aia aib aic aii ais as- asa asb asc asi ass baa bab bac bai bas bba bbb bbc bbi bbs bca bcb bcc bci bcs bi- bia bib bic bii bis bsa bsb bsc bsi bss c-- caa cab cac cai cas cba cbb cbc cbi cbs cca ccb ccc cci ccs ci- cia cib cic cii cis csa csb csc csi css ia- iaa iab iac iai ias iba ibb ibc ibi ibs ica icb icc ici ics iia iib iic iii iis is- isa isb isc isi iss saa sab sac sai sas sba sbb sbc sbi sbs sca scb scc sci scs sia sib sic sii sis ss- ssa ssb ssc ssi sss