a-a a-b aaa aab aak aao aap aar aas ab- aba abb abk abo abp abr abs aka akb akk ako akp akr aks aoa aob aok aoo aop aor aos ap- apa apb apk apo app apr aps ar- ara arb ark aro arp arr ars as- asa asb ask aso asp asr ass b-p baa bab bak bao bap bar bas bba bbb bbk bbo bbp bbr bbs bka bkb bkk bko bkp bkr bks boa bob bok boo bop bor bos bpa bpb bpo bpp bpr bps bra brb brk bro brp brr brs bsa bsb bsk bso bsp bsr bss ka- kaa kab kak kao kap kar kas kba kbb kbk kbo kbp kbr kbs kkb kkk kkp kkr kks koa kob kok koo kop kor kos kpa kpk kpo kpp kpr kps kra krk kro krp krr krs ksa ksb ksk kso ksp ksr kss oaa oab oak oao oap oar oas ob- oba obb obk obo obp obr obs oka okb okk oko okp okr oks oo- ooa oob ook ooo oop oor oos op- opa opb opk opo opp opr ops or- ora orb ork oro orp orr ors os- osa osb osk oso osp osr oss p-p paa pab pak pao pap par pas pba pbb pbk pbo pbp pbr pbs pka pkb pko pkp pkr pks poa pob pok poo pop por pos ppa ppb ppk ppo ppp ppr pps pra prb prk pro prp prr prs ps- psa psb psk pso psp psr pss ra- raa rab rak rao rap rar ras rba rbb rbk rbo rbp rbr rbs rkb rkk rko rkp rks roa rob rok roo rop ror ros rpa rpb rpk rpo rpp rpr rps rra rrb rrk rrp rrr rrs rsa rsb rsk rso rsp rsr rss saa sab sak sao sap sar sas sba sbb sbk sbo sbp sbr sbs sk- ska skb skk sko skp skr sks soa sob sok soo sop sor sos spa spb spk spo spp spr sps sr- sra srb srk sro srp srr srs ss- ssa ssb ssk sso ssp ssr sss