a-a a-b aaa aab aae aaf aao aap ab- aba abb abe abf abo abp aea aeb aee aef aeo aep af- afa afb afe aff afo afp aoa aob aoe aof aoo aop ap- apa apb ape apf apo app b-p baa bab bae baf bao bap bba bbb bbe bbf bbo bbp be- bea beb bee bef beo bep bfa bfb bfe bff bfo bfp boa bob boe bof boo bop bpa bpb bpe bpf bpo bpp eaa eab eae eaf eao eap eba ebb ebe ebf ebo ebp eea eeb eee eef eeo eep ef- efa efb efe eff efo efp eo- eoa eob eoe eof eoo eop ep- epa epb epe epf epo epp faa fab fae faf fao fap fba fbb fbe fbf fbo fbp fea feb fee fef feo fep ffa ffe fff ffo ffp foa fob foe fof foo fop fpa fpb fpe fpo fpp oaa oab oae oaf oao oap ob- oba obb obe obf obo obp oea oeb oee oef oeo oep of- ofa ofb ofe off ofo ofp oo- ooa oob oof ooo oop op- opa opb ope opf opo opp p-p paa pab pae paf pao pap pba pbb pbe pbf pbo pbp pea peb pee pef peo pep pfa pfb pfe pff pfo pfp poa pob poe pof poo pop ppa ppb ppe ppf ppo ppp