When you have solved the second part of "Know your Header", you can enter the flag here.
You will need to have solved "Know your Header (Part I)" for this challenge. Use the binary from Part I, named "challenge_encoded" to solve this.
NOTE: The format of the flag is ATR[], for example: ATR[foobar]. The flag must be submitted in full, including the ATR and square bracket parts.
The hint is in the file ".hint"