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. ")