a-a a-b a-c aaa aab aac aan aap aas ab- aba abb abc abn abp abs ac- aca acb acc acn acp acs an- ana anb anc ann anp ans ap- apa apb apc apn app aps as- asa asb asc asn asp ass b-p baa bab bac ban bap bas bba bbb bbc bbn bbp bbs bca bcb bcc bcn bcp bcs bna bnb bnc bnn bnp bns bpa bpb bpc bpn bpp bps bsa bsb bsc bsn bsp bss c-- caa cab cac can cap cas cba cbb cbc cbn cbp cbs cca ccb ccc ccn ccp ccs cn- cna cnb cnc cnn cnp cns cpa cpb cpc cpn cpp cps csa csb csc csn csp css naa nab nac nan nap nas nba nbb nbc nbn nbp nbs nca ncb ncc ncn ncp ncs nna nnb nnc nnn nnp nns npa npb npc npn npp nps nsa nsb nsc nsn nsp nss p-p paa pab pac pan pap pas pba pbb pbc pbn pbp pbs pca pcb pcc pcn pcp pcs pn- pna pnb pnc pnn pnp pns ppa ppb ppc ppn ppp pps ps- psa psb psc psn psp pss saa sab sac san sap sas sba sbb sbc sbn sbp sbs sca scb scc scn scp scs sna snb snc snn snp sns spa spb spc spn spp sps ss- ssa ssb ssc ssn ssp sss