aaaa aaac aaar aaca aacc aacr aact aara aarc aart aata aatc aatt ac-t acaa acac acar acat acca accc acct acr- acra acrc acrr acta actc actt arac arar arat arax arc- arca arct arr- arra arrc arrr arrt arta artc artr artx at-t at-x ataa atac atar atat atax atca atcc atcr atra atrc atrx atta attr axar axat caaa caac caat cac- caca cacc cacr cara carc carr cart carx cat- cata catc catt caxa ccaa ccac ccar ccat ccca cccc ccra ccrc ccrt cctc cctt crac crar crat crax crca crcc crcr crrt crtc ctca ctrc ctta cxxx raat rac- raca racc ract rara rata ratt raxa rcac rccc rctc rrat rrrr rtca rtcc taa- taar taat taca tacc tact tara tarc tarr tart tata tatr tatt tax- taxa taxt tcca tccc tctc traa trac trat trax trca trcc trra trtc trtr tttt txaa txtr xaar xact xara xcat xtar xtra xxxx