5568: AtCoder Quiz 2-AtCoder测验2（ABC219A)

 Problem Statement：

In the Kingdom of AtCoder, there is a standardized test of competitive programming proficiency.

An examinee will get a score out of $100$ and obtain a rank according to the score, as follows:

-   Novice, for a score not less than $0$ but less than $40$;
-   Intermediate, for a score not less than $40$ but less than $70$;
-   Advanced, for a score not less than $70$ but less than $90$;
-   Expert, for a score not less than $90$.

Xiaoniu took this test and got $X$ points.

Find the minimum number of extra points needed to go up one rank higher. If, however, his rank was Expert, print `expert`, as there is no higher rank than that.

在AtCoder王国，有一项标准化的竞技编程能力测试。

考生将获得一个0到100分的分数，并根据分数获得以下等级

    新手:分数不低于0但低于40:
    中级:分数不低于40但低于70;
    高级:分数不低于70但低于90;
    专家:分数不低于90。
小牛在这次考试中得到了X分。
请计算他至少还需要多少分才能提升到更高的等级。但是，如果他的等级已经是专家，请输出expert，因为没有比专家更高的等级了。

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