-ic a-a a-b a-c a-i aaa aab aac aaf aai aar aas ab- aba abb abc abf abi abr abs ac- aca acb acc acf aci acr acs af- afa afb afc aff afi afr afs ai- aia aib aic aif aii air ais ar- ara arb arc arf ari arr ars as- asa asb asc asf asi asr ass baa bab bac baf bai bar bas bba bbb bbc bbf bbi bbr bbs bca bcb bcc bcf bci bcr bcs bfa bfb bfc bff bfi bfr bfs bi- bia bib bic bif bii bir bis bra brb brf bri brr brs bsa bsb bsc bsf bsi bsr bss c-- caa cab cac caf cai car cas cba cbb cbc cbf cbi cbr cbs cca ccb ccc ccf cci ccr ccs cfa cfb cfc cff cfi cfr cfs ci- cia cib cic cif cii cir cis cra crb crc crf cri crr crs csa csb csc csf csi csr css faa fab fac faf fai far fas fba fbb fbc fbf fbi fbr fbs fca fcb fcc fcf fci fcr fcs ffa ffc fff ffi ffr ffs fia fib fic fif fii fir fis fra frb frc frf fri frr frs fsa fsb fsc fsf fsi fsr fss i-f ia- iaa iab iac iaf iai iar ias iba ibb ibc ibf ibi ibr ibs ica icb icc icf ici icr ics ifa ifb ifc iff ifi ifr ifs iia iib iic iif iii iir iis ir- ira irb irc irf iri irr irs is- isa isb isc isf isi isr iss ra- raa rab rac raf rai rar ras rba rbb rbc rbf rbi rbr rbs rca rcb rcc rcf rci rcr rcs rfa rfb rfc rff rfi rfr rfs ria rib ric rif rii rir ris rra rrb rrc rrf rri rrr rrs rsa rsb rsc rsf rsi rsr rss saa sab sac saf sai sar sas sba sbb sbc sbf sbi sbr sbs sca scb scc scf sci scr scs sfa sfb sfc sff sfi sfr sfs sia sib sic sif sii sir sis sr- sra srb src srf sri srr srs ss- ssa ssb ssc ssf ssi ssr sss