import java.io.*;
import java.util.*;
import java.math.*;

class Main {
	
	static int h , w;
	static String[] field;
	static int[] dx = {0,0,-1,1};
	static int[] dy = {-1,1,0,0};
	static boolean[][] isSearched;
	
	public static void out (Object o) {
		System.out.println(o);
	}
	
	public static int[] getBlank () {
		int start = -1;
		ArrayList<Integer> list = new ArrayList<Integer>();
		main:for (int i = 0; i < h; i++) {
			for (int j = 0; j < w; j++) {
				if (field[i].charAt(j) == '#' || isSearched[i][j]) continue;
				isSearched[i][j] = true;
				start = j << 5 | i;
				break main;
			}
		}
		list.add(start);
		Queue<Integer> queue = new LinkedList<Integer>();
		queue.add(start);
		while (!queue.isEmpty()) {
			int q = queue.poll();
			int x = q >> 5;
			int y = q & 15;
			for (int i = 0; i < dx.length; i++) {
				int moveX = x + dx[i];
				int moveY = y + dy[i];
				if (moveX < 0 || moveX >= w || moveY < 0 || moveY >= h) continue;
				if (field[moveY].charAt(moveX) == '#' || isSearched[moveY][moveX]) continue;
				list.add(moveX << 5 | moveY);
				isSearched[moveY][moveX] = true;
				queue.add(moveX << 5 | moveY);
			}
		}
		int[] ret = new int[list.size()];
		for (int i = 0; i < list.size(); i++)
			ret[i] = list.get(i);
		return ret;
	}
	
	public static int solve () {
		int ret = Integer.MAX_VALUE;
		int[] bl1 = getBlank();
		int[] bl2 = getBlank();
		//out(bl1.length + "," + bl2.length);
		for (int i = 0; i < bl1.length; i++) {
			int x1 = bl1[i] >> 5;
			int y1 = bl1[i] & 15;
			//out(x1 + "," + y1);
			for (int j = 0; j < bl2.length; j++) {
			int x2 = bl2[j] >> 5;
			int y2 = bl2[j] & 15;
				//out("(" + x1 + "," + y1 + ") - (" + x2 + "," + y2 + ")");
				ret = Math.min(ret , Math.abs(x1 - x2) + Math.abs(y1 - y2) - 1);
			}
		}
		return ret;
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		String[] line = br.readLine().split(" ");
		w = Integer.parseInt(line[0]);
		h = Integer.parseInt(line[1]);
		field = new String[h];
		isSearched = new boolean[h][w];
		for (int i = 0; i < h; i++) {
			field[i] = br.readLine();
		}
		
		out(solve());
	}
	
}