-al a-a a-b aaa aab aal aar aax ab- aba abb abl abr abx al- ala alb all alr alx ar- ara arb arl arr arx ax- axa axl axr axx baa bab bal bar bax bba bbb bbl bbr bbx bla blb bll blr blx bra brb brl brr brx bxb bxl bxx la- laa lab lal lar lax lba lbb lbl lbr lbx lla llb lll llr lra lrb lrr lxr lxx ra- raa rab ral rar rax rba rbb rbl rbr rbx rla rll rlr rra rrb rrl rrr rxr xaa xal xar xbl xbr xbx xla xlb xlr xrx xxl xxx