AT_abc425_f [ABC425F] Inserting Process

You are given a string $ T $ of length $ N $ consisting of lowercase English letters. Output, modulo $ 998244353 $ , the number of sequences of strings $ s=(s_0,s_1,\ldots,s_N) $ that satisfy all of the following conditions. - $ s_0 $ is an empty string. - For $ i=1,2,\ldots,N $ , the string $ s_{i} $ is obtained by inserting one arbitrary character at an arbitrary position (possibly beginning or end) in $ s_{i-1} $ . - $ s_N=T $

The input is given from Standard Input in the following format: > $ N $ $ T $

Output the answer.

### Sample Explanation 1 The sequences $ s $ that satisfy the conditions are the following three: - $ s=(\texttt{""}, \texttt{"a"} ,\texttt{"aa"} ,\texttt{"aab"} ) $ - $ s=(\texttt{""}, \texttt{"a"} ,\texttt{"ab"} ,\texttt{"aab"} ) $ - $ s=(\texttt{""}, \texttt{"b"} ,\texttt{"ab"} ,\texttt{"aab"} ) $ ### Constraints - $ 1\leq N\leq 22 $ - $ N $ is an integer. - $ T $ is a string of length $ N $ consisting of lowercase English letters.