Grid Path

There is a grid containing $N$ rows and $N$ columns. The cell at the $i^{th}$ row from the top and $j^{th}$ column from the left is a passable space if $S_{i,j}$ is `'.'` and a blocked cell if $S_{i,j}$ is `'#'`. Chef is at the top-left cell and wants to reach the bottom-right cell. Chef can move one cell down, or right to a passable cell. He can't leave the grid. If Chef is at the cell $(i,j)$,