bbbb bbpr bobb bobo boob boop boor boot bopp bor- boro borr bort botb boto bott bpot brob broo bror brot brrr btbp btob btor btrt bttb obbo obor obot obro oooo oort ootb ootp opo- opor oppo opto orbb orbo oro- oror orot orro orto oto- otoo otor otpp otro otto pobo poop poor poot pop- popo popp popt porb poro porr port poto pott pppo pppp pptt pro- prob proo prop prot prtp prtr ptop rbbb rbbr rob- robb robo robt roob roop roor root ropo roro rort roto rotr rott rpob rrrr rttp tbrb tbtp tobo tobt toor toot top- topo topp topt toro torp torr tort toto totr tott tppp tppr tptp tptr troo trop trot trpp trtr ttbb ttop tttt