a-a a-b a-c a-z aaa aab aac aar aas aaz ab- aba abb abc abr abs abz ac- aca acb acc acr acs acz ar- ara arb arc arr ars arz as- asa asb asc asr ass asz az- aza azb azs azz baa bab bac bar bas baz bba bbb bbc bbr bbs bca bcb bcc bcr bcs bcz bra brb brr brs brz bsa bsb bsc bsr bss bza bzr bzs bzz c-- caa cab cac car cas caz cba cbb cbc cbr cbs cbz cca ccb ccc ccr ccs ccz cra crb crc crr crs crz csa csb csc csr css csz cz- czc ra- raa rab rac rar ras raz rba rbb rbc rbr rbs rca rcb rcc rcr rcs rra rrb rrc rrr rrs rsa rsb rsc rsr rss rza rzb saa sab sac sar sas saz sba sbb sbc sbr sbs sca scb scc scr scs sr- sra srb src srr srs ss- ssa ssb ssc ssr sss ssz sza szr zaa zab zac zar zas zaz zbb zbc zbr zbs zcs zrs zsa zsz zzr zzs zzz