a-a a-b aaa aab aak aan aao aap aar ab- aba abb abk abn abo abp abr aka akb akk akn ako akp akr an- ana anb ank ann ano anp anr aoa aob aok aon aoo aop aor ap- apa apb apk apn apo app apr ar- ara arb ark arn aro arp arr b-p baa bab bak ban bao bap bar bba bbb bbk bbn bbo bbp bbr bka bkb bkk bkn bko bkp bkr bna bnb bnk bnn bno bnp bnr boa bob bok bon boo bop bor bpa bpb bpn bpo bpp bpr bra brb brk brn bro brp brr ka- kaa kab kak kan kao kap kar kba kbb kbk kbn kbo kbp kbr kkb kkk kkn kkp kkr kn- kna knk knn kno knp knr koa kob kok kon koo kop kor kpa kpk kpn kpo kpp kpr kra krk krn kro krp krr naa nab nak nan nao nap nar nba nbb nbk nbn nbo nbp nbr nka nkk nkn nko nkp nkr nna nnb nnk nnn nno nnp no- noa nob nok non noo nop nor npa npb npn npo npp npr nra nrb nrk nrn nro nrp nrr oaa oab oak oan oao oap oar ob- oba obb obk obn obo obp obr oka okb okk oko okp okr on- ona onb onk onn ono onp onr oo- ooa oob ook oon ooo oop oor op- opa opb opk opn opo opp opr or- ora orb ork orn oro orp orr p-p paa pab pak pan pao pap par pba pbb pbk pbn pbo pbp pbr pka pkb pkn pko pkp pkr pn- pna pnb pnk pnn pno pnp pnr poa pob pok pon poo pop por ppa ppb ppk ppn ppo ppp ppr pra prb prk prn pro prp prr ra- raa rab rak ran rao rap rar rba rbb rbk rbn rbo rbp rbr rkb rkk rko rkp rna rnb rnn rno rnp rnr roa rob rok ron roo rop ror rpa rpb rpk rpn rpo rpp rpr rra rrb rrk rrn rrp rrr