写代码：实现用户输入用户名和密码，当用户名为seven且密码为123时，显示登陆成功，不然失败，失败时容许重复输入三次。

# 实现用户输入用户名和密码，当用户名为seven且密码为123时，显示登陆成功，不然失败，失败时容许重复输入三次。


count = 0

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

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