P11030 'DABOI Round 1' Blessings Repeated

@[cyh20100812](https://www.luogu.com.cn/user/1051692) is respectfully called “Shengmu” (shèng mǔ) because of their strong abilities. > Shengmu is so dazzling. Thanks to Shengmu!

Shengmu is a debater, i.e. an ENTP. In one debate, her viewpoint is the string $S$. To convince the other side, she will emphasize it $k$ times, so her speech is the concatenation of $k$ copies of the string $S$ in order. As the rebutter, you may not be able to hear everything clearly, so you can only catch the keyword $T$. You need to find, in the string formed by concatenating $k$ copies of $S$, how many subsequences (not necessarily contiguous) are equal to $T$. Output the answer modulo $998244353$. --- **[Formal statement]** Given a positive integer $k$ and two strings $S, T$. Let the string $s$ be the string obtained by concatenating $k$ copies of $S$. Let $n=\vert s \vert$ and $m=\vert T \vert$. Let the answer set be $P=\{ (i_0,i_1,\dots,i_{m-1}) \mid 0\le i_0 < i_1 < \dots < i_{m-1} < n, \forall~0 \le j < m, s_{i_j}=T_j \}$. Compute $\vert P \vert \bmod 998244353$.

There are $3$ lines of input. Line $1$ contains one integer $k$. Line $2$ contains one string $S$. Line $3$ contains one string $T$.

Output one line containing one integer, the answer.

**[Explanation for Sample 1]** Repeat $S$ $2$ times to get $\texttt{stocyhorzstocyhorz}$. The answer set is $P=\{(3,4,5),(3,4,14),(3,13,14),(12,13,14) \}$, so $\vert P\vert=4$. --- **[Constraints]** For all testdata, $0