package no157;

import java.util.ArrayDeque;
import java.util.Scanner;

public class Main {
	static int[] di = {1,0,-1,0};
	static int[] dj = {0,1,0,-1};
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int w = sc.nextInt();
		int h = sc.nextInt();
		int[][] c = new int[h][w];
		int si = -1;
		int sj = -1;
		for(int i=0;i<h;i++) {
			String s = sc.next();
			for(int j=0;j<w;j++) {
				c[i][j] = s.charAt(j) == '#' ? 1 : 0;
				if (c[i][j] == 0 && si == -1) {
					si = i;
					sj = j;
				}
			}
		}

		int[][] dist = new int[h][w];
		for(int i=0;i<h;i++) {
			for(int j=0;j<w;j++) {
				dist[i][j] = 1<<29;
			}
		}
		dist[si][sj] = 0;
		ArrayDeque<Point> q = new ArrayDeque<>();
		q.offer(new Point(si,sj));
		int ans = 1 << 29;
		while(!q.isEmpty()) {
			Point p = q.pollFirst();
//			System.out.println(p);
			for(int i=0;i<4;i++) {
				int ni = p.i + di[i];
				int nj = p.j + dj[i];
				if (ni < 0 || ni >= h || nj < 0 || nj >= w) {
					continue;
				}
				int d = dist[p.i][p.j] + c[ni][nj];
				if (d < dist[ni][nj]) {
					dist[ni][nj] = d;
					if (c[p.i][p.j] == 1 && c[ni][nj] == 0 && dist[ni][nj] != 0) {
						ans = Math.min(ans,d);
					}else{
						if (c[ni][nj] == 0) {
							q.offerFirst(new Point(ni,nj));
						}else{
							q.offerLast(new Point(ni,nj));
						}
					}
				}
			}
		}
		System.out.println(ans);
	}
	static class Point {
		int i,j;
		public Point(int i,int j) {
			this.i = i;
			this.j = j;
		}
		public String toString() {
			return i + "," + j;
		}
	}
}