a-a a-b a-i a-z aaa aab aai aao aas aaz ab- aba abb abi abo abs abz ai- aia aib aii aio ais aiz aoa aob aoi aoo aos as- asa asb asi aso ass asz az- aza azb azi azo azs azz baa bab bai bao bas baz bba bbb bbi bbo bbs bi- bia bib bii bio bis biz boa bob boi boo bos boz bsa bsb bsi bso bss bza bzo bzs bzz ia- iaa iab iai iao ias iaz iba ibb ibi ibo ibs ibz iia iib iii iio iis io- ioa iob ioi ioo ios is- isa isb isi iso iss iza izi izo izz o-i oaa oab oai oao oas ob- oba obb obi obo obs oia oib oii oio ois oiz oo- ooa oob ooi ooo oos os- osa osb osi oso oss oza ozo ozs ozz saa sab sai sao sas saz sba sbb sbi sbo sbs sia sib sii sio sis soa sob soi soo sos soz ss- ssa ssb ssi sso sss ssz sza szi zaa zab zai zao zas zaz zbb zbs zia zib zio zis ziz zo- zoa zob zoi zoo zos zsa zsi zsz zzs zzz