aaaa aaab aaav aaba aabb aabt aaoo aata aatt aava abaa abab abat abb- abba abbb abbo abbt aboa abob aboo abot abov abta abva aoba at-t ataa atab atat atob atot atta atto avab avao avat avot avva avvo baaa baat baba babb babo bata bato batt bava bbbb boab boat boba bobb bobo boob boot bota botb boto bott bova bovo btaa btob bttb obba obbo obot ooaa ooba oooo ootb oto- otoo otov otta otto ovo- ovoo ovot taa- taat taba tabb tabo taoa tata tatb tato tatt tatv tava tavo tbta toab toat toba tobo tobt tooa toot tota toto tott tova tovo ttab ttbb tttt tvtv vaat vata vato vatt vava voat voot vota voto vvob vvvv