a-a a-b a-c aaa aab aac aae aak aan aao aap ab- aba abb abc abe abk abn abo abp ac- aca acb acc ace ack acn aco acp aea aeb aec aee aek aen aeo aep aka akb akc ake akk akn ako akp an- ana anb anc ane ank ann ano anp aoa aob aoc aoe aok aon aoo aop ap- apa apb apc ape apk apn apo app b-p baa bab bac bae bak ban bao bap bba bbb bbc bbe bbk bbn bbo bbp bca bcb bcc bce bck bcn bco bcp be- bea beb bec bee bek ben beo bep bka bkb bkc bke bkk bkn bko bkp bna bnb bnc bne bnk bnn bno bnp boa bob boc boe bok bon boo bop bpa bpb bpc bpe bpn bpo bpp c-- caa cab cac cae cak can cao cap cba cbb cbc cbe cbk cbn cbo cbp cca ccb ccc cce cck ccn cco ccp ce- cea ceb cec cee cek cen ceo cep cka ckb ckc cko cn- cna cnb cnc cne cnn cno cnp co- coa cob coc coe cok con coo cop cpa cpb cpc cpe cpk cpn cpo cpp eaa eab eac eae eak ean eao eap eba ebb ebc ebe ebk ebn ebo ebp ec- eca ecb ecc ece eck ecn eco eea eeb eec eee eek een eeo eep eka ekb ekc eke eko ekp en- ena enb enc ene enk enn eno enp eo- eoa eob eoc eoe eok eon eoo eop ep- epa epb epc epe epn epo epp ka- kaa kab kac kae kak kan kao kap kba kbb kbc kbe kbk kbn kbo kbp kca kcb kcc kce kck kcn kcp ke- kea keb kec kee kek ken keo kep kkb kkc kke kkk kkn kkp kn- kna knc kne knk knn kno knp koa kob koc koe kok kon koo kop kpa kpc kpe kpk kpn kpo kpp naa nab nac nae nak nan nao nap nba nbb nbc nbe nbk nbn nbo nbp nca ncb ncc nce nck ncn nco ncp ne- nea neb nec nee nek nen neo nep nka nkc nke nkk nkn nko nkp nna nnb nnc nne nnk nnn nno nnp no- noa nob noc noe nok non noo nop npa npb npc npe npn npo npp oaa oab oac oae oak oan oao oap ob- oba obb obc obe obk obn obo obp oc- oca ocb occ ock ocn oco ocp oea oeb oec oee oen oeo oep oka okb okc oke okk oko okp on- ona onb onc one onk onn ono onp oo- ooa oob ooc ook oon ooo oop op- opa opb opc ope opk opn opo opp p-p paa pab pac pae pak pan pao pap pba pbb pbc pbe pbk pbn pbo pbp pca pcb pcc pce pck pcn pco pcp pea peb pec pee pek pen peo pep pka pkb pkc pke pkn pko pkp pn- pna pnb pnc pne pnk pnn pno pnp poa pob poc poe pok pon poo pop ppa ppb ppc ppe ppk ppn ppo ppp