username = "123"
userpassword = "123456"
while True:
    if i>0:
        name = input("请输入用户名:")
        password = input("请输入密码:")
        i-=1     #i=i-1
        if name == username and password == userpassword:
            print("登录成功!")
            break
        if name != username: 
            print("print("用户名错误请重新输入") 
        if password != userpassword:
            print("密码错误!请重新输入") 
        print("密码错误用户名错误请重新输入：") 
    else:
        print("滚！")
        exit()
print("欢迎来到贝尔编程!")