写代码：实现用户输入用户名和密码，当用户名为seven或者Alex且密码为123时，显示登录成功，否则失败，失败时允许重复输入三次。

#  实现用户输入用户名和密码，当用户名为seven或者Alex且密码为123时，显示登录成功，否则失败，失败时允许重复输入三次。

count = 0

while count < 3:
    username = input("Please enter your username: ")
    password = input("Please enter your password: ")
    if username == "seven" and password == "123":
        print("%s login successful." %username)
        break
    elif username == "alex" and password == "123":
        print("%s login successful." %username)
        break
    else:
        print("login failed.")
    count += 1

if count == 3:
    print("the max input is 3 times. ")