a-a a-b aaa aab aae aan aap aas ab- aba abb abe abn abp abs aea aeb aee aen aep aes an- ana anb ane ann anp ans ap- apa apb ape apn app aps as- asa asb ase asn asp ass b-p baa bab bae ban bap bas bba bbb bbe bbn bbp bbs be- bea beb bee ben bep bes bna bnb bne bnn bnp bns bpa bpb bpe bpn bpp bps bsa bsb bse bsn bsp bss eaa eab eae ean eap eas eba ebb ebe ebn ebp ebs eea eeb eee een eep ees en- ena enb ene enn enp ens ep- epa epb epe epn epp eps es- esa esb ese esn esp ess naa nab nae nan nap nas nba nbb nbe nbn nbp nbs ne- nea neb nee nen nep nes nna nnb nne nnn nnp nns npa npb npe npn npp nps nsa nsb nse nsn nsp nss p-p paa pab pae pan pap pas pba pbb pbe pbn pbp pbs pea peb pee pen pep pes pn- pna pnb pne pnn pnp pns ppa ppb ppe ppn ppp pps ps- psa psb pse psn psp pss saa sab sae san sap sas sba sbb sbe sbn sbp sbs se- sea seb see sen sep ses sna snb sne snn snp sns spa spb spe spn spp sps ss- ssa ssb sse ssn ssp sss