loading_number=3
while True:
    name = input("请输入用户名:")
    if name != username:
        print("用户名错误")
        loading_number-=1
        print("你还可以登录："+str(number)+"次")
        if loading_number==0:
            print("登录次数以到达，拒绝登录")
            exit()
        continue
password=input("请输入密码")
if name == username and password == userpassword:
    print("登录成功!")
else:
    print("密码错误") 
    loading_number-=1
    print("你还可以登录："+str(number)+"次")
    if loading_number==0:
        print("登录次数以到达，拒绝登录")
        exit()
print("欢迎来到贝尔编程!")