bbbb bibb bibi birb biri birr birt biru birx bitt bitu bitx bixi brit brix brrr brut brux btrt bttb bubb bubi bubu buir buit buiu buix bur- burb buri burr burt buru but- buti butt ibri ibtb iiii iiit iitr iitt iri- irix irri irti itri itur iuiu ixxi rbbb rbbr rib- ribu riri riti ritt ritu rrrr rubb rubi rubu ruit ruri ruru ruti rutt rutu tbit tbrb tibi tibu tiit tiiu tirb tiri tirr tiru titi titt titu tixt tri- trib trit trix trtr trub trut truu trux ttbb tttt tubb tubr tubu tuit tuiu tuix turb turi turr turt turu tuti tutt tutu txii txtr ubbi ubii ubir ubit uirr urbi urib uriu urix urri urur urut utri utti uttu uuri uuuu xibu xiii xixi xuri xuxu xxii xxix xxxi xxxx