a-a a-b aaa aab aae aaf aao aap aas ab- aba abb abe abf abo abp abs aea aeb aee aef aeo aep aes af- afa afb afe aff afo afp afs aoa aob aoe aof aoo aop aos ap- apa apb ape apf apo app aps as- asa asb ase asf aso asp ass b-p baa bab bae baf bao bap bas bba bbb bbe bbf bbo bbp bbs be- bea beb bee bef beo bep bes bfa bfb bfe bff bfo bfp bfs boa bob boe bof boo bop bos bpa bpb bpe bpf bpo bpp bps bsa bsb bse bsf bso bsp bss eaa eab eae eaf eao eap eas eba ebb ebe ebf ebo ebp ebs eea eeb eee eef eeo eep ees ef- efa efb efe eff efo efp efs eo- eoa eob eoe eof eoo eop eos ep- epa epb epe epf epo epp eps es- esa esb ese esf eso esp ess faa fab fae faf fao fap fas fba fbb fbe fbf fbo fbp fbs fea feb fee fef feo fep fes ffa ffe fff ffo ffp ffs foa fob foe fof foo fop fos fpa fpb fpe fpo fpp fps fsa fsb fse fsf fso fsp fss oaa oab oae oaf oao oap oas ob- oba obb obe obf obo obp obs oea oeb oee oef oeo oep oes of- ofa ofb ofe off ofo ofp ofs oo- ooa oob oof ooo oop oos op- opa opb ope opf opo opp ops os- osa osb ose osf oso osp oss p-p paa pab pae paf pao pap pas pba pbb pbe pbf pbo pbp pbs pea peb pee pef peo pep pes pfa pfb pfe pff pfo pfp pfs poa pob poe pof poo pop pos ppa ppb ppe ppf ppo ppp pps ps- psa psb pse psf pso psp pss saa sab sae saf sao sap sas sba sbb sbe sbf sbo sbp sbs se- sea seb see sef seo sep ses sfa sfb sfe sff sfo sfp sfs soa sob soe sof soo sop sos spa spb spe spf spo spp sps ss- ssa ssb sse ssf sso ssp sss