username_list = []
password_list = []
#REGISTER
username = None
password = None
def register():
    #SETTING USERNAME
    username = input("Enter your desired username: ")
    while len(username) < 6:
        username = input("Your username must be at least 6 characters long, try again: ")
    if True:
        print("You've successfully set your username.")
        username_list.append(username)

    #SETTING PASSWORD
    password = input("Enter your desired password: ")
    while (len(password) < 6) or (sum(c.isdigit() for c in password) == 0):
        password = input("Your password must be at least 6 characters long and must contain at least 1 digit, try again: ")
    if True:
        print("You've successfully set your password.")
        print("<------------------------------------>")
        password_list.append(password)
register()

#LOG IN
us_er = None
pa_ss = None
def ask_info():
    us_er = input("Enter your username: ")
    pa_ss = input("Enter your password: ")
def log_in():
    ask_info()
    while (us_er and pa_ss) in (username_list and password_list):
        print("Failed login, given username or password might be wrong.")
    else:
        print("successfully logged in.")
log_in()