Checks a website. I currently have no way of checking if the website exists, therefore please be sure that the website exists. Otherwise, it'll crash. (runtime error)

webcheck.py

import time, requests, sys

print("\n"*100)
url = str(input("INSERT URL HERE: "))
if url[:8] != "https://":
    if url[:7] != "http://":
        print("not a url.")
        sys.exit(0)
    sys.exit(0)
while True:
    check = requests.get(url)
    if check.status_code != 200:
        if check.status_code == 429:
            print(f"Checking {url}: Not working.        status: {check.status_code}")
            print("status 429 requires longer wait.")
            time.sleep(int((check.headers['retry-after'])))
            sys.exit(0)
        else:
            print(f"Checking {url}: Not working.        status: {check.status_code}")
            time.sleep(2)
    else:
        print(f"Checking {url}: Working conditions. status: {check.status_code}")
        time.sleep(2)