a-a a-c aaa aac aaf aak aas ac- aca acc acf ack acs af- afa afc aff afk afs aka akc akk aks as- asa asc asf ask ass c-- caa cac caf cak cas cca ccc ccf cck ccs cfa cfc cff cfk cfs cka ckc cks csa csc csf csk css faa fac faf fak fas fca fcc fcf fck fcs ffa ffc fff ffk ffs fka fkc fkf fkk fsa fsc fsf fsk fss ka- kaa kac kaf kak kas kca kcc kck kcs kfa kfc kff kfs kkc kkk kks ksa ksc ksf ksk kss saa sac saf sak sas sca scc scf sck scs sfa sfc sff sfk sfs sk- ska skc skf skk sks ss- ssa ssc ssf ssk sss