Typos are a very important part of ICPC problem statements. ICPC research department found out that there exist $3$ main categories of typos: \begin{itemize} \item One letter of the word was accidentally skipped (for example, \texttt{sell} is written instead of \texttt{shell}) \item One extra letter was accidentally inserted (for example, \texttt{horny} is written instead of \texttt{horn}) \item One letter was accidentally replaced with another (for example, \texttt{ictc} is written instead of \texttt{icpc}) \end{itemize} ICPC research department now considers an alphabet consisting of first $n$ Latin letters and a word $s$. They wonder: how many distinct words can you obtain by making in $s$ \textbf{exactly one} typo? \InputFile The first line contains a single integer $n$ ($1 \le n \le 26$) --- the size of the alphabet. The second line contains a string $s$ ($2 \le |s| \le 100000$), which consists only of the first $n$ letters of the Latin alphabet. \OutputFile Output the number of distinct words that you can obtain by making in $s$ \textbf{exactly one} typo. \textbf{Note that the word with typos can contain only letters among the first $n$ letters of the Latin alphabet, too.} For example, for $n = 3$ and $s =$ \texttt{cab} you can't obtain \t{dab} by mistyping \t{c}. \Note From the string \texttt{abcd} from the sample we can obtain the following strings: \begin{verbatim} abc abd acd bcd aacd abad abbd abca abcb abcc abdd accd adcd bbcd cbcd dbcd aabcd abacd abbcd abcad abcbd abccd abcda abcdb abcdc abcdd abdcd acbcd adbcd babcd cabcd dabcd \end{verbatim}