username = "python"
userpassword = "123456"
while True:
    name = input("请输入用户名:")
    password = input("请输入密码:")
    if name == username and password == userpassword:
        print("登录成功!")
        break

    elif name !=username:
        print("输入用户名错误!请重新输入")
        
    else:
        print("输入密码错误!请重新输入")
       
print("欢迎来到贝尔编程!")