a-a a-b a-c aaa aab aac aan aap ab- aba abb abc abn abp ac- aca acb acc acn acp an- ana anb anc ann anp ap- apa apb apc apn app b-p baa bab bac ban bap bba bbb bbc bbn bbp bca bcb bcc bcn bcp bna bnb bnc bnn bnp bpa bpb bpc bpn bpp c-- caa cab cac can cap cba cbb cbc cbn cbp cca ccb ccc ccn ccp cn- cna cnb cnc cnn cnp cpa cpb cpc cpn cpp naa nab nac nan nap nba nbb nbc nbn nbp nca ncb ncc ncn ncp nna nnb nnc nnn nnp npa npb npc npn npp p-p paa pab pac pan pap pba pbb pbc pbn pbp pca pcb pcc pcn pcp pn- pna pnb pnc pnn pnp ppa ppb ppc ppn ppp