This challenge was quite boring and generic. It seems, that not the tiniest bit of love went into making this task.

1. Run binwalk -e challenge.jpg to extract any hidden files (of well-known formats)
2. Find 196 pictures, most of which are flags of countries, in the output folder
3. Browse trough the pictures and find jp.png, which has written some generic hex string on it.

4. This string is the flag: 6C76648BEDF6B6C5A9D48564FC68868D

Summing up, the biggest challenge was recognising the flag as THE flag, because the absence of a specified flag format.