bbbb bbpr bbrc bcbc bcbp bccc bcor bcpp bobb bobo boco boob booc boop boor bopp bor- boro borr bpcp bprc brcb brob broc broo bror brrr c-bo cbbc cbcc cbcp cbcr cbpc cbpp ccbc cccb cccc cccp ccob ccoc ccpp ccpr ccrc ccrp cobb cobo coco cocp coob coop copo copp copr cor- corb corc coro corp corr cpbc crbc crcc crcr crob croc croo crop cror crpc obbo obor obro ocbc occc ocpp ocro ocrr oocr oooo opo- opor oppo orbb orbo orco oro- oror orpc orro pbcc pboc pcbc pccc pcpb pcpp pcrc pobo poco poop poor pop- popc popo popp porb porc poro porr ppcc pppo pppp pprc prbc prcc prcp pro- prob proc proo prop rbbb rbbr rcbc rcbo rccb rccc rcpo rob- robb robo rocc roco roob roop roor ropo rorc roro rpob rrrr