## 「CF1349D」 Slime and Biscuits

Slime and his $n$ friends are at a party. Slime has designed a game for his friends to play.
At the beginning of the game, the $i$-th player has $a_i$
biscuits. At each second, Slime will choose a biscuit randomly uniformly among all $a_1 + a_2 + \ldots + a_n$ biscuits, and the owner of this biscuit will give it to a random uniform player among $n-1$ players except himself. The game stops when one person will have all the biscuits.

As the host of the party, Slime wants to know the expected value of the time that the game will last, to hold the next activity on time.

For convenience, as the answer can be represented as a rational number $\frac{p}{q}$
​for coprime $p$ and $q$ , you need to find the value of $(p \cdot q^{-1})\mod 998\,244\,353$. You can prove that $q\mod 998\,244\,353 \neq 0$

## 「HNOI2015」亚瑟王

（即 ii 等于 nn），则结束这一轮；否则，考虑下一张卡牌。

## [六省联考2017] 分手是祝愿

B 君在玩一个游戏，这个游戏由 n 个灯和 n 个开关组成，给定这 n 个灯的初始状态，下标为从 1 到 nn 的正整数。