#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 $P$.