模拟登录验证三次机会

chance = 3
while chance > 0:
    name = input("请输入用户名:")
    pwd = input("请输入密码:")
    if name == "alex" and pwd == "123":
        print("登录成功")
        break
    chance -= 1
    print("用户名或密码错误，你还有%d次机会" % chance)
else:
    print("登录失败，账号锁定")