a-a a-b aaa aab aan aao aap aar ab- aba abb abn abo abp abr an- ana anb ann ano anp anr aoa aob aon aoo aop aor ap- apa apb apn apo app apr ar- ara arb arn aro arp arr b-p baa bab ban bao bap bar bba bbb bbn bbo bbp bbr bna bnb bnn bno bnp bnr boa bob bon boo bop bor bpa bpb bpn bpo bpp bpr bra brb brn bro brp brr naa nab nan nao nap nar nba nbb nbn nbo nbp nbr nna nnb nnn nno nnp no- noa nob non noo nop nor npa npb npn npo npp npr nra nrb nrn nro nrp nrr oaa oab oan oao oap oar ob- oba obb obn obo obp obr on- ona onb onn ono onp onr oo- ooa oob oon ooo oop oor op- opa opb opn opo opp opr or- ora orb orn oro orp orr p-p paa pab pan pao pap par pba pbb pbn pbo pbp pbr pn- pna pnb pnn pno pnp pnr poa pob pon poo pop por ppa ppb ppn ppo ppp ppr pra prb prn pro prp prr ra- raa rab ran rao rap rar rba rbb rbn rbo rbp rbr rna rnb rnn rno rnp rnr roa rob ron roo rop ror rpa rpb rpn rpo rpp rpr rra rrb rrn rrp rrr