#AT2153. E - RLE
E - RLE
当前没有测试数据。
E - RLE
Score : $500$ points
Problem Statement
Consider the following procedure of, given a string $X$ consisting of lowercase English alphabets, obtaining a new string:
- Split the string $X$ off at the positions where two different characters are adjacent to each other.
- For each string $Y$ that has been split off, replace $Y$ with a string consisting of the character which $Y$ consists of, followed by the length of $Y$.
- Concatenate the replaced strings without changing the order.
For example, aaabbcccc is divided into aaa,bb,cccc, which are replaced by a3,b2,c4, respectively, which in turn are concatenated without changing the order, resulting in a3b2c4.If the given string is aaaaaaaaaa , the new string is a10 .
Find the number, modulo $P$, of strings $S$ of lengths $N$ consisting of lowercase English alphabets, such that the length of $T$ is smaller than that of $S$, where $T$ is the string obtained by the procedure above against the string $S$.
Constraints
- $1 \le N \le 3000$
- $10^8 \le P \le 10^9$
- $N$ and $P$ are integers.
- $P$ is a prime.
Input
Input is given from Standard Input in the following format:
Output
Print the answer.
3 998244353
26
Those strings of which the $1$-st, $2$-nd, and $3$-rd characters are all the same satisfy the condition.
For example, aaa becomes a3, which satisfies the condition, while abc becomes a1b1c1, which does not.
2 998244353
0
Note that if a string is transformed into another string of the same length, such as aa that becomes a2, it does not satisfy the condition.
5 998244353
2626
Strings like aaabb and aaaaa satisfy the condition.
3000 924844033
607425699
Find the number of strings satisfying the condition modulo $P$.