a-a a-b aaa aab aae aak aap aax ab- aba abb abe abk abp abx aea aeb aee aek aep aex aka akb ake akk akp ap- apa apb ape apk app apx ax- axa axe axk axp axx b-p baa bab bae bak bap bax bba bbb bbe bbk bbp bbx be- bea beb bee bek bep bex bka bkb bke bkk bkp bkx bpa bpb bpe bpp bpx bxb bxx eaa eab eae eak eap eax eba ebb ebe ebk ebp ebx eea eeb eee eek eep eex eka ekb eke ekp ep- epa epb epe epp epx ex- exa exe exp exx ka- kaa kab kae kak kap kax kba kbb kbe kbk kbp kbx ke- kea keb kee kek kep kex kkb kke kkk kkp kpa kpe kpk kpp p-p paa pab pae pak pap pax pba pbb pbe pbk pbp pbx pea peb pee pek pep pex pka pkb pke pkp ppa ppb ppe ppk ppp ppx pxe pxk xaa xak xap xbe xbx xee xep xex xkb xke xpa xpb xpe xpp xxp xxx