a-a a-b a-i aaa aab aai aak aar aas ab- aba abb abi abk abr abs ai- aia aib aii aik air ais aka akb aki akk akr aks ar- ara arb ari ark arr ars as- asa asb asi ask asr ass baa bab bai bak bar bas bba bbb bbi bbk bbr bbs bi- bia bib bii bik bir bis bka bkb bkk bkr bks bra brb bri brk brr brs bsa bsb bsi bsk bsr bss ia- iaa iab iai iar ias iba ibb ibi ibk ibr ibs iia iib iii iir iis ika ikb iki ikk ikr iks ir- ira irb iri irk irr irs is- isa isb isi isk isr iss ka- kaa kab kai kak kar kas kba kbb kbi kbk kbr kbs kia kib kii kik kir kis kkb kki kkk kkr kks kra kri krk krr krs ksa ksb ksi ksk ksr kss ra- raa rab rai rak rar ras rba rbb rbi rbk rbr rbs ria rib rii rik rir ris rkb rkk rks rra rrb rri rrk rrr rrs rsa rsb rsi rsk rsr rss saa sab sai sak sar sas sba sbb sbi sbk sbr sbs sia sib sii sik sir sis sk- ska skb ski skk skr sks sr- sra srb sri srk srr srs ss- ssa ssb ssi ssk ssr sss