Score : $500$ points
Consider the following procedure of, given a string $X$ consisting of lowercase English alphabets, obtaining a new string:
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 $S$.
Input is given from Standard Input in the following format:
$N$ $P$
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 $P$.