b-p bbb bbk bbo bbp bbr bkb bkk bko bkp bkr bob bok boo bop bor bpb bpo bpp bpr brb brk bro brp brr kbb kbk kbo kbp kbr kkb kkk kkp kkr kob kok koo kop kor kpk kpo kpp kpr krk kro krp krr ob- obb obk obo obp obr okb okk oko okp okr oo- oob ook ooo oop oor op- opb opk opo opp opr or- orb ork oro orp orr p-p pbb pbk pbo pbp pbr pkb pko pkp pkr pob pok poo pop por ppb ppk ppo ppp ppr prb prk pro prp prr rbb rbk rbo rbp rbr rkb rkk rko rkp rob rok roo rop ror rpb rpk rpo rpp rpr rrb rrk rrp rrr