a-a a-b aaa aab aak aap aas ab- aba abb abk abp abs aka akb akk akp aks ap- apa apb apk app aps as- asa asb ask asp ass b-p baa bab bak bap bas bba bbb bbk bbp bbs bka bkb bkk bkp bks bpa bpb bpp bps bsa bsb bsk bsp bss ka- kaa kab kak kap kas kba kbb kbk kbp kbs kkb kkk kkp kks kpa kpk kpp kps ksa ksb ksk ksp kss p-p paa pab pak pap pas pba pbb pbk pbp pbs pka pkb pkp pks ppa ppb ppk ppp pps ps- psa psb psk psp pss saa sab sak sap sas sba sbb sbk sbp sbs sk- ska skb skk skp sks spa spb spk spp sps ss- ssa ssb ssk ssp sss