Can you retrieve the flag from this program? You will need to submit your interactive solution to the judge.
The judge will run
main.c. You must interact with the judge with a solution through the standard input and output streams. Anything the judge outputs will be in your standard input stream, and anything you output to standard output will be forwarded to the judge as input. If your solution successfully causes the judge to print the flag to its standard error stream, you will receive AC. Otherwise, you will receive WA. Note that at no point during the judging will your program receive the flag.
This problem is from DMOJ Capture The Flag '20. For more details, please view the contest page.