a-a a-c aaa aac aad aae aaf aak ac- aca acc acd ace acf ack ad- ada adc add ade adf adk aea aec aed aee aef aek af- afa afc afd afe aff afk aka akc akd ake akk c-- caa cac cad cae caf cak cca ccc ccd cce ccf cck cda cdc cdd cde cdf cdk ce- cea cec ced cee cef cek cfa cfc cfd cfe cff cfk cka ckc ckd daa dac dad dae daf dak dca dcc dcd dce dcf dck dda ddc ddd dde ddf ddk de- dea dec ded dee def dek dfa dfc dfd dfe dff dfk dka dkc dke dkk eaa eac ead eae eaf eak ec- eca ecc ecd ece ecf eck ed- eda edc edd ede edf edk eea eec eed eee eef eek ef- efa efc efd efe eff eka ekc ekd eke ekf faa fac fad fae faf fak fca fcc fcd fce fcf fck fda fdc fdd fde fdf fdk fea fec fed fee fef fek ffa ffc ffd ffe fff ffk fka fkc fkf fkk ka- kaa kac kad kae kaf kak kca kcc kcd kce kck kda kdc kde kdf kdk ke- kea kec ked kee kef kek kfa kfc kfd kff kkc kke kkk