a-a a-b aaa aab aae aan aao aap ab- aba abb abe abn abo abp aea aeb aee aen aeo aep an- ana anb ane ann ano anp aoa aob aoe aon aoo aop ap- apa apb ape apn apo app b-p baa bab bae ban bao bap bba bbb bbe bbn bbo bbp be- bea beb bee ben beo bep bna bnb bne bnn bno bnp boa bob boe bon boo bop bpa bpb bpe bpn bpo bpp eaa eab eae ean eao eap eba ebb ebe ebn ebo ebp eea eeb eee een eeo eep en- ena enb ene enn eno enp eo- eoa eob eoe eon eoo eop ep- epa epb epe epn epo epp naa nab nae nan nao nap nba nbb nbe nbn nbo nbp ne- nea neb nee nen neo nep nna nnb nne nnn nno nnp no- noa nob noe non noo nop npa npb npe npn npo npp oaa oab oae oan oao oap ob- oba obb obe obn obo obp oea oeb oee oen oeo oep on- ona onb one onn ono onp oo- ooa oob oon ooo oop op- opa opb ope opn opo opp p-p paa pab pae pan pao pap pba pbb pbe pbn pbo pbp pea peb pee pen peo pep pn- pna pnb pne pnn pno pnp poa pob poe pon poo pop ppa ppb ppe ppn ppo ppp