bbbb bftt bibb bibi bibo biff bifi bio- bioi biot bito bitt bobb bobi bobo boff boi- boii boit boob boof boot botb boti boto bott btob bttb ffff ffii fftf fiff fifi fifo fift fiii fiti fitt fobt fofo foof foot foti foto fott ftii ibfi ibot ibtb ifbb ifit ifto iiii iiio iiit iioi iioo iitt iobi ioii ioio ioit ioof iooi iooo iotf ioto itif itof itoi itoo ittf itto obbo obit oboi obot off- offo ofit oiii oiti oobi ooff oooo ootb otif otit oto- otof otoo otti otto tbit tfot tibi tiff tifo tift tiit titi tito titt tobi tobo tobt toff tofi tofo toft toit toof toot toti toto tott ttbb ttff tttt