Given a chessboard of size $n \times m$, i.e., with $n$ rows and $m$ columns.

There is only one piece on this chessboard --- a rook. It is located in the bottom left corner. There are no other pieces.

Recall that a rook can move any number of cells horizontally or vertically in one move, but not diagonally.

Find the number of cells the rook can move to in one move.

\begin{center}
\includegraphics[width=8cm, height=8cm, bb=0 0 550 550]{uoi-2022-2-chess.png}


\small{The image shows a traditional chessboard of size $8 \times 8$. On this board, the rook can move to all the cells marked in green. There are a total of $14$ such cells, so the answer is $14$.}
\end{center}