aaaa aaab aaac aaba aabb aabc aabt aaca aacb aacc aact aata aatc aatt abaa abab abac abat abb- abba abbb abbt abca abcb abcc abct abta ac-t acaa acab acac acat acba acca accc acct acta actc actt at-t ataa atab atac atat atca atcc atta baaa baat baba babb bac- baca bacc bact bata batc batt bbbb bcaa bcat bcbc bcca bccc bctc btaa btcc bttb caaa caab caac caat caba cac- caca cacc cat- cata catb catc catt cbac cbat cbbc cbca cbcc cbct cbta cbtc ccaa ccab ccac ccat ccba ccbc ccca cccb cccc cctb cctc cctt ctab ctba ctca ctta taa- taat taba tabb tabc taca tacc tact tata tatb tatt tbca tbcb tbcc tbta tcca tccc tctc ttab ttbb tttt