Hello 2018
F
Strongly Connected Tournament
Codeforces
2800
原题
← EG →
翻译中…

There is a chess tournament in All-Right-City. $*n*$ players were invited to take part in the competition. The tournament is held by the following rules:

翻译中…
  1. Initially, each player plays one game with every other player. There are no ties;
  2. After that, the organizers build a complete directed graph with players as vertices. For every pair of players there is exactly one directed edge between them: the winner of their game is the startpoint of this edge and the loser is the endpoint;
  3. After that, the organizers build a condensation of this graph. The condensation of this graph is an acyclic complete graph, therefore it has the only Hamiltonian path which consists of strongly connected components of initial graph $*A*_{1} → *A*_{2} → ... → *A*_{*k*}$.
  4. The players from the first component $*A*_{1}$ are placed on the first image places, the players from the component $*A*_{2}$ are placed on the next image places, and so on.
  5. To determine exact place of each player in a strongly connected component, all the procedures from 1 to 5 are repeated recursively inside each component, i.e. for every $*i* = 1, 2, ..., *k*$ players from the component $*A*_{*i*}$ play games with each other again, and so on;
  6. If a component consists of a single player, then he has no more rivals, his place is already determined and the process stops.
翻译中…

The players are enumerated with integers from $1$ to $*n*$. The enumeration was made using results of a previous tournament. It is known that player $*i*$ wins player $*j*$ ($*i* < *j*$) with probability $*p*$.

翻译中…

You need to help to organize the tournament. Find the expected value of total number of games played by all the players.

翻译中…

It can be shown that the answer can be represented as image, where $*P*$ and $*Q*$ are coprime integers and image. Print the value of $*P*·*Q*^{ - 1}$ modulo $998244353$.

翻译中…

If you are not familiar with any of the terms above, you can read about them here.

翻译中…

Input

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The first line of input contains a single integer $*n*$ ($2 ≤ *n* ≤ 2000$) — the number of players.

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The second line contains two integers $*a*$ and $*b*$ ($1 ≤ *a* < *b* ≤ 100$) — the numerator and the denominator of fraction image.

翻译中…

Output

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In the only line print the expected value of total number of games played by all the players. Print the answer using the format above.

翻译中…

Note

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In the first example the expected value is $4$.

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In the second example the expected value is image.

翻译中…

In the third example the expected value is image.

翻译中…

样例

Input #1
3
1 2
Output #1
4
InputCopy OutputCopy
Input #2
3
4 6
Output #2
142606340
InputCopy OutputCopy
Input #3
4
1 2
Output #3
598946623
InputCopy OutputCopy
题目信息
题号
913F
所属比赛
时间限制
2 s
内存限制
256 MB
标签
动态规划
图论
数学
概率论

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。