a-a a-b aaa aab aae aag aak ab- aba abb abe abg abk aea aeb aee aeg aek ag- aga agb age agg agk aka akb ake akg akk baa bab bae bag bak bba bbb bbe bbg bbk be- bea beb bee beg bek bga bgb bge bgg bgk bka bkb bke bkg bkk eaa eab eae eag eak eba ebb ebe ebg ebk eea eeb eee eeg eek ega egb ege egg eka ekb eke ekg gaa gab gae gag gak gba gbe gbg gbk ge- gea geb gee geg gek gga ggb ggg gka gkb ka- kaa kab kae kag kak kba kbb kbe kbk ke- kea keb kee keg kek kga kgb kkb kke kkk