a-a a-b a-i aaa aab aad aaf aai aak ab- aba abb abd abf abi abk ad- ada adb add adf adi adk af- afa afb afd aff afi afk ai- aia aib aid aif aii aik aka akb akd aki akk baa bab bad baf bai bak bba bbb bbd bbf bbi bbk bda bdb bdd bdf bdi bdk bfa bfb bfd bff bfi bi- bia bib bid bif bii bik bka bkb bkf bkk daa dab dad daf dai dak dba dbb dbd dbf dbi dbk dda ddb ddd ddf ddi ddk dfa dfb dfd dff dfi dfk di- dia dib did dif dii dik dka dkb dki dkk faa fab fad faf fai fak fba fbb fbd fbf fbi fbk fda fdb fdd fdf fdi fdk ffa ffd fff ffi ffk fia fib fid fif fii fik fka fkb fkf fki fkk i-d i-f ia- iaa iab iad iaf iai iba ibb ibd ibf ibi ibk ida idb idd idf idi idk ifa ifb ifd iff ifi iia iib iid iif iii ika ikb ikf iki ikk ka- kaa kab kad kaf kai kak kba kbb kbd kbf kbi kbk kda kdb kdf kdk kfa kfd kff kfi kia kib kid kif kii kik kkb kki kkk