a-a a-b a-c aaa aab aac aae aan aap ab- aba abb abc abe abn abp ac- aca acb acc ace acn acp aea aeb aec aee aen aep an- ana anb anc ane ann anp ap- apa apb apc ape apn app b-p baa bab bac bae ban bap bba bbb bbc bbe bbn bbp bca bcb bcc bce bcn bcp be- bea beb bec bee ben bep bna bnb bnc bne bnn bnp bpa bpb bpc bpe bpn bpp c-- caa cab cac cae can cap cba cbb cbc cbe cbn cbp cca ccb ccc cce ccn ccp ce- cea ceb cec cee cen cep cn- cna cnb cnc cne cnn cnp cpa cpb cpc cpe cpn cpp eaa eab eac eae ean eap eba ebb ebc ebe ebn ebp ec- eca ecb ecc ece ecn eea eeb eec eee een eep en- ena enb enc ene enn enp ep- epa epb epc epe epn epp naa nab nac nae nan nap nba nbb nbc nbe nbn nbp nca ncb ncc nce ncn ncp ne- nea neb nec nee nen nep nna nnb nnc nne nnn nnp npa npb npc npe npn npp p-p paa pab pac pae pan pap pba pbb pbc pbe pbn pbp pca pcb pcc pce pcn pcp pea peb pec pee pen pep pn- pna pnb pnc pne pnn pnp ppa ppb ppc ppe ppn ppp