a-a a-b aaa aab aan aap aas ab- aba abb abn abp abs an- ana anb ann anp ans ap- apa apb apn app aps as- asa asb asn asp ass b-p baa bab ban bap bas bba bbb bbn bbp bbs bna bnb bnn bnp bns bpa bpb bpn bpp bps bsa bsb bsn bsp bss naa nab nan nap nas nba nbb nbn nbp nbs nna nnb nnn nnp nns npa npb npn npp nps nsa nsb nsn nsp nss p-p paa pab pan pap pas pba pbb pbn pbp pbs pn- pna pnb pnn pnp pns ppa ppb ppn ppp pps ps- psa psb psn psp pss saa sab san sap sas sba sbb sbn sbp sbs sna snb snn snp sns spa spb spn spp sps ss- ssa ssb ssn ssp sss