a-a a-b a-i aaa aab aae aai aak ab- aba abb abe abi abk aea aeb aee aei aek ai- aia aib aie aii aik aka akb ake aki akk baa bab bae bai bak bba bbb bbe bbi bbk be- bea beb bee bei bek bi- bia bib bie bii bik bka bkb bke bkk eaa eab eae eai eak eba ebb ebe ebi ebk eea eeb eee eek eia eib eie eii eik eka ekb eke eki ia- iaa iab iae iai iba ibb ibe ibi ibk ie- iea iee iei iek iia iib iie iii ika ikb ike iki ikk ka- kaa kab kae kai kak kba kbb kbe kbi kbk ke- kea keb kee kei kek kia kib kie kii kik kkb kke kki kkk