- Cell.jar and inpattern.txt should be in the same folder
- Open Cell.jar : # java -jar Cell.jar
- Click InPat button : https://imgur.com/wWalHHO
- Type the letter E in the program area : https://imgur.com/4aefPQn
- Click parse : https://imgur.com/Wr2nIPm
- And then click step until the counter == 17 : https://imgur.com/V1cHTKu
- Click the outpat button, and check outpat.txt : 1 1 . 1 . . . . 1 1 . 1 1 . . . 1 1 . . . . 1 . 1 1 . . . 1 1 . 1 1 . 1 . 1 1 . 1 1 1 . . 1 1
- Replace dots : 11010000110110001100001011000110110101101110011
- Convert it to hex and then ascii : 686C61636B73 >> hlacks
- flag : nactf{hlacks}