## 「CodeForces 1366D」 Two Divisors

You are given 𝑛 integers 𝑎1,𝑎2,…,𝑎𝑛.

## 「CodeForces 1158C」Permutation recovery

Vasya has written some permutation 𝑝1,𝑝2,…,𝑝𝑛 of integers from 1 to 𝑛, so for all 1≤𝑖≤𝑛 it is true that 1≤𝑝𝑖≤𝑛 and all 𝑝1,𝑝2,…,𝑝𝑛 are different. After that he wrote 𝑛 numbers 𝑛𝑒𝑥𝑡1,𝑛𝑒𝑥𝑡2,…,𝑛𝑒𝑥𝑡𝑛. The number 𝑛𝑒𝑥𝑡𝑖 is equal to the minimal index 𝑖<𝑗≤𝑛, such that 𝑝𝑗>𝑝𝑖. If there is no such 𝑗 let's let's define as 𝑛𝑒𝑥𝑡𝑖=𝑛+1.

## 「ICPC Central Europe Regional Contest 2019」 G. K==S

Progressive hard octave rock tunes (so-called “phorts”) are written using a specifific music notation. This flflavor of rock is built on just 13 difffferent note pitches, other pitches (in other octaves)are considered to be an outdated musical ballast. Each note can be either a long one or a shortone. Consequently, there are exactly 26 difffferent notes in the rock.

## 「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。