a-a a-b aaa aab aad aaf aao aap aar aas ab- aba abb abd abf abo abp abr abs ad- ada adb add adf ado adp adr ads af- afa afb afd aff afo afp afr afs aoa aob aod aof aoo aop aor aos ap- apa apb apd apf apo app apr aps ar- ara arb ard arf aro arp arr ars as- asa asb asd asf aso asp asr ass b-p baa bab bad baf bao bap bar bas bba bbb bbd bbf bbo bbp bbr bbs bda bdb bdd bdf bdo bdp bdr bds bfa bfb bfd bff bfo bfp bfr bfs boa bob bod bof boo bop bor bos bpa bpb bpd bpf bpo bpp bpr bps bra brb brd brf bro brp brr brs bsa bsb bsd bsf bso bsp bsr bss daa dab dad daf dao dap dar das dba dbb dbd dbf dbo dbp dbr dbs dda ddb ddd ddf ddo ddp ddr dds dfa dfb dfd dff dfo dfp dfr dfs doa dob dod dof doo dop dor dos dpa dpb dpd dpf dpo dpp dpr dps dra drb drd dro drp drr drs dsa dsb dsd dsf dso dsp dsr dss faa fab fad faf fao fap far fas fba fbb fbd fbf fbo fbp fbr fbs fda fdb fdd fdf fdo fdp fdr fds ffa ffd fff ffo ffp ffr ffs foa fob fof foo fop for fos fpa fpb fpd fpo fpp fpr fps fra frb frd frf fro frp frr frs fsa fsb fsd fsf fso fsp fsr fss oaa oab oad oaf oao oap oar oas ob- oba obb obd obf obo obp obr obs oda odb odd odf odo odp odr ods of- ofa ofb ofd off ofo ofp ofr ofs oo- ooa oob ood oof ooo oop oor oos op- opa opb opd opf opo opp opr ops or- ora orb ord orf oro orp orr ors os- osa osb osd osf oso osp osr oss p-p paa pab pad paf pao pap par pas pba pbb pbd pbf pbo pbp pbr pbs pda pdb pdd pdf pdo pdp pdr pds pfa pfb pfd pff pfo pfp pfr pfs poa pob pod pof poo pop por pos ppa ppb ppd ppf ppo ppp ppr pps pra prb prd prf pro prp prr prs ps- psa psb psd psf pso psp psr pss ra- raa rab rad raf rao rap rar ras rba rbb rbd rbf rbo rbp rbr rbs rda rdb rdd rdf rdo rdp rdr rds rfa rfb rfd rff rfo rfp rfr rfs roa rob rod rof roo rop ror ros rpa rpb rpd rpf rpo rpp rpr rps rra rrb rrd rrf rrp rrr rrs rsa rsb rsd rsf rso rsp rsr rss saa sab sad saf sao sap sar sas sba sbb sbd sbf sbo sbp sbr sbs sda sdb sdd sdf sdo sdp sdr sds sfa sfb sfd sff sfo sfp sfr sfs soa sob sod sof soo sop sor sos spa spb spd spf spo spp spr sps sr- sra srb srd srf sro srp srr srs ss- ssa ssb ssd ssf sso ssp ssr sss