a-a a-t aaa aad aaf aas aat ad- ada add adf ads adt af- afa afd aff afs aft as- asa asd asf ass ast at- ata atd atf ats att daa dad daf das dat dda ddd ddf dds ddt dfa dfd dff dfs dft dsa dsd dsf dss dst dta dtd dtf dts dtt faa fad faf fas fat fda fdd fdf fds fdt ffa ffd fff ffs fft fsa fsd fsf fss fst fta ftd ftf fts ftt saa sad saf sas sat sda sdd sdf sds sdt sfa sfd sff sfs sft ss- ssa ssd ssf sss sst sta std stf sts stt taa tad taf tas tat tda tdd tdf tds tdt tfa tfd tff tfs tft tsa tsd tsf tss tst tta ttd ttf tts ttt