a-a a-c aaa aac aaf aan aas ac- aca acc acf acn acs af- afa afc aff afn afs an- ana anc anf ann ans as- asa asc asf asn ass c-- caa cac caf can cas cca ccc ccf ccn ccs cfa cfc cff cfn cfs cn- cna cnc cnf cnn cns csa csc csf csn css faa fac faf fan fas fca fcc fcf fcn fcs ffa ffc fff ffn ffs fna fnc fnf fnn fns fsa fsc fsf fsn fss naa nac naf nan nas nca ncc ncf ncn ncs nfa nfc nff nfn nfs nna nnc nnf nnn nns nsa nsc nsf nsn nss saa sac saf san sas sca scc scf scn scs sfa sfc sff sfn sfs sna snc snf snn sns ss- ssa ssc ssf ssn sss