bbbb bblb bibb bibi bibl bili bill bilt bilu bitt bitu blbt blit blub blut bttb bubb bubi bubu buit buiu bulb buli bull bult bulu but- buti butt ibtb ibtl iiii iiit iitt ilit ill- illi illt ilut itil itll iuiu libu liii lilb lili lill lilt lilu litb liti litl litt litu liut llll ltbl ltib luit luli lull lulu luti tbil tbit tibi tibu tiit tiiu till tilt titi titt titu tlli ttbb tttt ttul tubb tubu tuil tuit tuiu tuli tull tulu tuti tutl tutt tutu ubbi ubii ubit ubli ulli ulti ultt ulul util utti uttu uulu uuuu