a-a a-b a-c aaa aab aac aae aaf aak aao aap ab- aba abb abc abe abf abk abo abp ac- aca acb acc ace acf ack aco acp aea aeb aec aee aef aek aeo aep af- afa afb afc afe aff afk afo afp aka akb akc ake akk ako akp aoa aob aoc aoe aof aok aoo aop ap- apa apb apc ape apf apk apo app b-p baa bab bac bae baf bak bao bap bba bbb bbc bbe bbf bbk bbo bbp bca bcb bcc bce bcf bck bco bcp be- bea beb bec bee bef bek beo bep bfa bfb bfc bfe bff bfo bfp bka bkb bkc bke bkf bkk bko bkp boa bob boc boe bof bok boo bop bpa bpb bpc bpe bpf bpo bpp c-- caa cab cac cae caf cak cao cap cba cbb cbc cbe cbf cbk cbo cbp cca ccb ccc cce ccf cck cco ccp ce- cea ceb cec cee cef cek ceo cep cfa cfb cfc cfe cff cfk cfo cfp cka ckb ckc cko co- coa cob coc coe cof cok coo cop cpa cpb cpc cpe cpf cpk cpo cpp eaa eab eac eae eaf eak eao eap eba ebb ebc ebe ebf ebk ebo ebp ec- eca ecb ecc ece ecf eck eco eea eeb eec eee eef eek eeo eep ef- efa efb efc efe eff efo efp eka ekb ekc eke ekf eko ekp eo- eoa eob eoc eoe eof eok eoo eop ep- epa epb epc epe epf epo epp faa fab fac fae faf fak fao fap fba fbb fbc fbe fbf fbk fbo fbp fca fcb fcc fce fcf fck fco fcp fea feb fec fee fef fek feo fep ffa ffc ffe fff ffk ffo ffp fka fkb fkc fkf fkk fkp foa fob foc foe fof fok foo fop fpa fpb fpc fpe fpk fpo fpp ka- kaa kab kac kae kaf kak kao kap kba kbb kbc kbe kbf kbk kbo kbp kca kcb kcc kce kck kcp ke- kea keb kec kee kef kek keo kep kfa kfc kff kfo kkb kkc kke kkk kkp koa kob koc koe kof kok koo kop kpa kpc kpe kpf kpk kpo kpp oaa oab oac oae oaf oak oao oap ob- oba obb obc obe obf obk obo obp oc- oca ocb occ ocf ock oco ocp oea oeb oec oee oef oeo oep of- ofa ofb ofc ofe off ofo ofp oka okb okc oke okk oko okp oo- ooa oob ooc oof ook ooo oop op- opa opb opc ope opf opk opo opp p-p paa pab pac pae paf pak pao pap pba pbb pbc pbe pbf pbk pbo pbp pca pcb pcc pce pcf pck pco pcp pea peb pec pee pef pek peo pep pfa pfb pfc pfe pff pfk pfo pfp pka pkb pkc pke pkf pko pkp poa pob poc poe pof pok poo pop ppa ppb ppc ppe ppf ppk ppo ppp