Getting Started with Python - User Login Program

_flag = False 
count = 0 
users = [['ziv', '123'], ['alex', '12345']] 
while count < 3: 
    username = input('Username:') 
    password = input('Password: ') 
    for user_item in users: 
        if username == user_item[0] and password == user_item[1]: 
            print('Login successful') 
            _flag = True # Change the login success flag to True 
            break # Used to jump out of the for loop 
    else: 
        print('Username or password error') # The for loop is executed normally (successful login will be broken, the else will not be executed, and vice versa), and then execute else 
    if _flag: 
        break # Used to jump out of the while loop 
    count += 1 
else : 
    print('Username or password is wrong more than three times!') # Log in successfully while being broken, will not execute else, otherwise execute