import java.util.Scanner;

public class Main {
	
	static int W, H;
	static char C[][];
	static int mAns = Integer.MAX_VALUE;
	
	public static void main(String[] args) {
		readMap();
		
		int start[] = serchCavity();
		replaceCavity(start[0], start[1], '+');
		
		for(int i=0; i<H; i++) {
			for(int j=0; j<W; j++) {
				if(C[i][j] == '.') {
					solve(j, i, 0);
				}
			}
		}
		System.out.println(mAns-1);
	}
	
	static void solve(int j, int i, int step) {
		
		if(i==0 || i==H-1) return;
		if(j==0 || j==W-1) return;
		
		if(C[i][j] == '+') {
			mAns = Math.min(mAns, step);
			return;
		}
		
		C[i][j] = '.';
		
		if(C[i][j+1] != '.') solve(j+1, i  , step+1);
		if(C[i+1][j] != '.') solve(j  , i+1, step+1);
		if(C[i][j-1] != '.') solve(j-1, i  , step+1);
		if(C[i-1][j] != '.') solve(j  , i-1, step+1);
		
		C[i][j] = '#';
	}
	
	static void readMap() {
		Scanner sc = new Scanner(System.in);
		W = sc.nextInt();
		H = sc.nextInt();
		C = new char[H][W];
		
		for(int i=0; i<H; i++) {
			String line = sc.next();
			for(int j=0; j<W; j++) {
				C[i][j] = line.charAt(j);
			}
		}
	}
		
	static int[] serchCavity() {
		int ret[] = new int[2];
		
		for(int i=0; i<H; i++) {
			for(int j=0; j<W; j++) {
				if(C[i][j] == '.') {
					ret[0] = j;
					ret[1] = i;
					return ret;
				}
			}
		}
		throw new IllegalArgumentException();
	}
	
	static void replaceCavity(int j, int i, char v) {
		
		if(C[i][j] != '.') return;
		C[i][j] = v;
		
		replaceCavity(j+1, i  , v);
		replaceCavity(j  , i+1, v);
		replaceCavity(j-1, i  , v);
		replaceCavity(j  , i-1, v);
	}
}