a-be aaaa aaab aaae aaba aabb aabt aaea aata aatt abaa abab abae abat abax abb- abba abbb abbe abbt abee abet abta aeta aett aetx at-t at-x ataa atab atae atat atax atea atee atex atta atte axat ba-x baaa baat baba babb babe bata bate batt baxt bbbb bbeb bbet beat beba bebb bebe beeb beet beta bete bett btaa btex bttb eaba eata eate ebba eeea eeee eeta eete eext etat etee etta ette exa- exta exte taa- taat taba tabb tabe tata tatb tate tatt tax- taxa taxe taxt tbta teat teba teet teta tete tett tetx texa text ttab ttbb tttt txaa xate xbee xexe xtea xxxx