Minimum Moves to Reach the Farm's Bottom-Right

You are given a farm represented as an $n \times m$ grid. Each cell in the grid is either open (denoted by '.') or blocked (denoted by '#'). A tractor is placed at the top-left corner of the grid, and your task is to determine the minimum number of moves required to get the tractor from the top-left cell to the bottom-right cell. Moves can only be made in the four cardinal directions: up, down, left, and right. If the starting cell or the destination cell is blocked, or if there is no valid path, return -1.

The number of cells in the grid is $n \times m$, and a move consists of transitioning from one cell to an adjacent cell.

inputFormat

Input is read from standard input (stdin). The first line contains two integers $n$ and $m$, representing the number of rows and columns respectively. This is followed by $n$ lines, each containing a string of length $m$, where each character is either '.' (an open cell) or '#' (a blocked cell).

outputFormat

Output a single integer on standard output (stdout), which is the minimum number of moves needed to reach the bottom-right cell from the top-left cell. If it is impossible to reach the destination, output -1.## sample

5 6
#..#.#
##.#.#
#.##..
#....#
######

-1