n=0
username1="admin"
password1="123456"
while n<3:
username = input("username:")
password = input("password:")
if(username==username1 and password==password1):
print("欢迎admin登录系统")
break
else:
print("用户名或者密码错误，请重新输入")
n=n+1else:
print("错误的次数为3，退出程序")
