# THIS CODE IS MY OWN WORK, IT WAS WRITTEN WITHOUT CONSULTING
# CODE WRITTEN BY OTHER STUDENTS. NIR LEVY

username = input("user name: ")
password = input("password: ")

def letter_and_digit(stringer):
    str.isalnum(stringer)

def is_valid(username, password):
    if username == password: return False
    passlength = len(password)
    if passlength < 8: return False
    letter_and_digit(password)
    letter_and_digit(username)

def main(username, password):
    is_valid(username,password)
    if is_valid == True: print("Password is valid")
    else: print("Password is invalid")

main(username,password)