This is the file to solve Pieces challenge in beginner's Section.
Download main.java. You will see string comparison with "9|2/9/:|4/7|8|4/2/1/2/9/" string. Enter this input in python3 main.py you will get the flag add it to proper format

Original writeup (https://github.com/kartiksachdeva3/CTFwriteups/tree/master/rgbCTF-2020).