a-a a-b a-c aaa aab aac aak aap aas ab- aba abb abc abk abp abs ac- aca acb acc ack acp acs aka akb akc akk akp aks ap- apa apb apc apk app aps as- asa asb asc ask asp ass b-p baa bab bac bak bap bas bba bbb bbc bbk bbp bbs bca bcb bcc bck bcp bcs bka bkb bkc bkk bkp bks bpa bpb bpc bpp bps bsa bsb bsc bsk bsp bss c-- caa cab cac cak cap cas cba cbb cbc cbk cbp cbs cca ccb ccc cck ccp ccs cka ckb ckc cks cpa cpb cpc cpk cpp cps csa csb csc csk csp css ka- kaa kab kac kak kap kas kba kbb kbc kbk kbp kbs kca kcb kcc kck kcp kcs kkb kkc kkk kkp kks kpa kpc kpk kpp kps ksa ksb ksc ksk ksp kss p-p paa pab pac pak pap pas pba pbb pbc pbk pbp pbs pca pcb pcc pck pcp pcs pka pkb pkc pkp pks ppa ppb ppc ppk ppp pps ps- psa psb psc psk psp pss saa sab sac sak sap sas sba sbb sbc sbk sbp sbs sca scb scc sck scp scs sk- ska skb skc skk skp sks spa spb spc spk spp sps ss- ssa ssb ssc ssk ssp sss