-al a-a a-b a-t aaa aab aaf aal aat ab- aba abb abf abl abt af- afa afb aff afl aft al- ala alb alf all alt at- ata atb atf atl att baa bab baf bal bat bba bbb bbf bbl bbt bfa bfb bff bfl bft bla blb blf bll blt bta btb btf btl btt faa fab faf fal fat fba fbb fbf fbl fbt ffa fff ffl fft fla flb flf fll flt fta ftb ftf ftl ftt la- laa lab laf lal lat lba lbb lbf lbl lbt lfa lfb lff lfl lft lla llb llf lll llt lta ltb ltf ltl ltt taa tab taf tal tat tba tbb tbf tbl tbt tfa tfb tff tfl tft tla tlf tll tlt tta ttb ttf ttl ttt