a-a a-b a-c a-t aaa aab aac aat aaw ab- aba abb abc abt abw ac- aca acb acc act acw at- ata atb atc att atw aw- awa awb awc awt aww baa bab bac bat baw bba bbb bbc bbt bbw bca bcb bcc bct bta btb btc btt btw bwa bwb bwc c-- caa cab cac cat caw cba cbb cbc cbt cbw cca ccb ccc cct ccw cta ctb ctc ctt ctw cw- cwa cwb cwc cwt taa tab tac tat taw tba tbb tbc tbt tca tcb tcc tct tcw tta ttb ttc ttt ttw twa twb twc twt tww waa wab wac wat waw wba wbb wbc wbt wbw wca wcb wcc wct wcw wta wtb wtc wtt wtw wwa wwc wwt www