-ic a-a a-b a-c a-i aaa aab aac aaf aai aak aar aas ab- aba abb abc abf abi abk abr abs ac- aca acb acc acf aci ack acr acs af- afa afb afc aff afi afk afr afs ai- aia aib aic aif aii aik air ais aka akb akc aki akk akr aks ar- ara arb arc arf ari ark arr ars as- asa asb asc asf asi ask asr ass baa bab bac baf bai bak bar bas bba bbb bbc bbf bbi bbk bbr bbs bca bcb bcc bcf bci bck bcr bcs bfa bfb bfc bff bfi bfr bfs bi- bia bib bic bif bii bik bir bis bka bkb bkc bkf bkk bkr bks bra brb brf bri brk brr brs bsa bsb bsc bsf bsi bsk bsr bss c-- caa cab cac caf cai cak car cas cba cbb cbc cbf cbi cbk cbr cbs cca ccb ccc ccf cci cck ccr ccs cfa cfb cfc cff cfi cfk cfr cfs ci- cia cib cic cif cii cik cir cis cka ckb ckc cki cks cra crb crc crf cri crk crr crs csa csb csc csf csi csk csr css faa fab fac faf fai fak far fas fba fbb fbc fbf fbi fbk fbr fbs fca fcb fcc fcf fci fck fcr fcs ffa ffc fff ffi ffk ffr ffs fia fib fic fif fii fik fir fis fka fkb fkc fkf fki fkk fra frb frc frf fri frk frr frs fsa fsb fsc fsf fsi fsk fsr fss i-f ia- iaa iab iac iaf iai iar ias iba ibb ibc ibf ibi ibk ibr ibs ica icb icc icf ici ick icr ics ifa ifb ifc iff ifi ifr ifs iia iib iic iif iii iir iis ika ikb ikc ikf iki ikk ikr iks ir- ira irb irc irf iri irk irr irs is- isa isb isc isf isi isk isr iss ka- kaa kab kac kaf kai kak kar kas kba kbb kbc kbf kbi kbk kbr kbs kca kcb kcc kci kck kcr kcs kfa kfc kff kfi kfs kia kib kic kif kii kik kir kis kkb kkc kki kkk kkr kks kra krc krf kri krk krr krs ksa ksb ksc ksf ksi ksk ksr kss ra- raa rab rac raf rai rak rar ras rba rbb rbc rbf rbi rbk rbr rbs rca rcb rcc rcf rci rcr rcs rfa rfb rfc rff rfi rfk rfr rfs ria rib ric rif rii rik rir ris rkb rkc rkf rkk rks rra rrb rrc rrf rri rrk rrr rrs rsa rsb rsc rsf rsi rsk rsr rss saa sab sac saf sai sak sar sas sba sbb sbc sbf sbi sbk sbr sbs sca scb scc scf sci sck scr scs sfa sfb sfc sff sfi sfk sfr sfs sia sib sic sif sii sik sir sis sk- ska skb skc skf ski skk skr sks sr- sra srb src srf sri srk srr srs ss- ssa ssb ssc ssf ssi ssk ssr sss