a-a a-b aaa aab aad aan aap ab- aba abb abd abn abp ad- ada adb add adn adp an- ana anb and ann anp ap- apa apb apd apn app b-p baa bab bad ban bap bba bbb bbd bbn bbp bda bdb bdd bdp bna bnb bnd bnn bnp bpa bpb bpd bpn bpp daa dab dad dan dap dba dbb dbd dbn dbp dda ddb ddd ddn ddp dna dnb dnd dnn dnp dpa dpb dpd dpn dpp naa nab nad nan nap nba nbb nbd nbn nbp nda ndb ndd ndn ndp nna nnb nnn nnp npa npb npd npn npp p-p paa pab pad pan pap pba pbb pbd pbn pbp pda pdb pdd pdn pdp pn- pna pnb pnd pnn pnp ppa ppb ppd ppn ppp