a-a a-b a-i a-z aaa aab aai aar aaz ab- aba abb abi abr abz ai- aia aib aii air aiz ar- ara arb ari arr arz az- aza azb azi azz baa bab bai bar baz bba bbb bbi bbr bi- bia bib bii bir biz bra brb bri brr brz bza bzr bzz ia- iaa iab iai iar iaz iba ibb ibi ibr ibz iia iib iii iir ir- ira irb iri irr iza izi izz ra- raa rab rai rar raz rba rbb rbi rbr ria rib rii rir riz rra rrb rri rrr rza rzb zaa zab zai zar zaz zbb zbr zia zib zir ziz zzr zzz