a-a a-b a-i a-t aaa aab aaf aai aat ab- aba abb abf abi abt af- afa afb aff afi aft ai- aia aib aif aii ait at- ata atb atf ati att baa bab baf bai bat bba bbb bbf bbi bbt bfa bfb bff bfi bft bi- bia bib bif bii bit bta btb btf bti btt faa fab faf fai fat fba fbb fbf fbi fbt ffa fff ffi fft fia fib fif fii fit fta ftb ftf fti ftt i-f ia- iaa iab iaf iai iat iba ibb ibf ibi ibt ifa ifb iff ifi ift iia iib iif iii iit ita itb itf iti itt taa tab taf tai tat tba tbb tbf tbi tbt tfa tfb tff tfi tft tia tib tif tii tit tta ttb ttf tti ttt