bbbb bibb bibi bibo bio- bioi biot birb biri biro birr birt bito bitt bivi bobb bobi bobo boi- boii boit boob boor boot bor- bori boro borr bort botb boti boto bott bovi bovo brio brit brob broo bror brot brrr brvi btob btor btrt bttb btvi ibot ibri ibro ibtb iiii iiio iiit iioi iioo iitr iitt iobi ioii ioio ioit iooi iooo iori ioto iri- irio irob irov irri irti itoi itoo itor itri itto ivbv ivor obbo obit oboi obor obot obri obro obvi oiii oirt oiti oobi oooo oort ootb orbb orbi orbo ori- orio orit oro- oror orot orri orro orto orvr otit oto- otoo otor otov otro otti otto ovi- ovo- ovoo ovot rbbb rbbr rib- ribo riot riri riti rito ritt rivo rob- robb robi robo robt roio roir roit roob rooi roor root rori roro rort roti roto rotr rott rovi rovo rrrr rtvi tbit tbrb tbvi tibi tiit tirb tiri tiro tirr titi tito titt tivi tivo tobi tobo tobt toit toor toot tori toro torr tort torv toti toto totr tott tovo tri- trib trio trit troi troo trot trtr ttbb tttt tvri tvro tvrr tvtv viii virb viri viro virr virt viti vito vitt vivi vivo voio voir voit voor voot vor- vori voro vort voto vrio vrot vrto vt-i vvob vvvv