a-a a-b a-t aaa aab aaf aao aap aar aas aat ab- aba abb abf abo abp abr abs abt af- afa afb aff afo afp afr afs aft aoa aob aof aoo aop aor aos aot ap- apa apb apf apo app apr aps apt ar- ara arb arf aro arp arr ars art as- asa asb asf aso asp asr ass ast at- ata atb atf ato atp atr ats att b-p baa bab baf bao bap bar bas bat bba bbb bbf bbo bbp bbr bbs bbt bfa bfb bff bfo bfp bfr bfs bft boa bob bof boo bop bor bos bot bpa bpb bpf bpo bpp bpr bps bpt bra brb brf bro brp brr brs brt bsa bsb bsf bso bsp bsr bss bst bta btb btf bto btp btr bts btt faa fab faf fao fap far fas fat fba fbb fbf fbo fbp fbr fbs fbt ffa fff ffo ffp ffr ffs fft foa fob fof foo fop for fos fot fpa fpb fpo fpp fpr fps fpt fra frb frf fro frp frr frs frt fsa fsb fsf fso fsp fsr fss fst fta ftb ftf fto ftp ftr fts ftt oaa oab oaf oao oap oar oas oat ob- oba obb obf obo obp obr obs obt of- ofa ofb off ofo ofp ofr ofs oft oo- ooa oob oof ooo oop oor oos oot op- opa opb opf opo opp opr ops opt or- ora orb orf oro orp orr ors ort os- osa osb osf oso osp osr oss ost ot- ota otb otf oto otp otr ots ott p-p paa pab paf pao pap par pas pat pba pbb pbf pbo pbp pbr pbs pbt pfa pfb pff pfo pfp pfr pfs pft poa pob pof poo pop por pos pot ppa ppb ppf ppo ppp ppr pps ppt pra prb prf pro prp prr prs prt ps- psa psb psf pso psp psr pss pst pt- pta ptb ptf pto ptp ptr pts ptt ra- raa rab raf rao rap rar ras rat rba rbb rbf rbo rbp rbr rbs rbt rfa rfb rff rfo rfp rfr rfs rft roa rob rof roo rop ror ros rot rpa rpb rpf rpo rpp rpr rps rpt rra rrb rrf rrp rrr rrs rrt rsa rsb rsf rso rsp rsr rss rst rta rtb rtf rto rtp rtr rts rtt saa sab saf sao sap sar sas sat sba sbb sbf sbo sbp sbr sbs sbt sfa sfb sff sfo sfp sfr sfs sft soa sob sof soo sop sor sos sot spa spb spf spo spp spr sps spt sr- sra srb srf sro srp srr srs srt ss- ssa ssb ssf sso ssp ssr sss sst sta stb stf sto stp str sts stt taa tab taf tao tap tar tas tat tba tbb tbf tbo tbp tbr tbs tbt tfa tfb tff tfo tfp tfr tfs tft to- toa tob tof too top tor tos tot tpa tpb tpf tpo tpp tpr tps tpt tra trb trf tro trp trr trs trt tsa tsb tsf tso tsp tsr tss tst tta ttb ttf tto ttp ttr tts ttt