a-a a-b a-t aaa aab aaf aak aar aat ab- aba abb abf abk abr abt af- afa afb aff afk afr aft aka akb akk akr ar- ara arb arf ark arr art at- ata atb atf atr att baa bab baf bak bar bat bba bbb bbf bbk bbr bbt bfa bfb bff bfr bft bka bkb bkf bkk bkr bkt bra brb brf brk brr brt bta btb btf btk btr btt faa fab faf fak far fat fba fbb fbf fbk fbr fbt ffa fff ffk ffr fft fka fkb fkf fkk fkt fra frb frf frk frr frt fta ftb ftf ftk ftr ftt k-t ka- kaa kab kaf kak kar kat kba kbb kbf kbk kbr kfa kff kkb kkk kkr kkt kra krf krk krr krt kta ktb ktf ktk ktr ktt ra- raa rab raf rak rar rat rba rbb rbf rbk rbr rbt rfa rfb rff rfk rfr rft rkb rkf rkk rkt rra rrb rrf rrk rrr rrt rta rtb rtf rtk rtr rtt taa tab taf tak tar tat tba tbb tbf tbk tbr tbt tfa tfb tff tfk tfr tft tka tkb tkk tkr tkt tra trb trf trk trr trt tta ttb ttf ttk ttr ttt