import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	
	static int W, H;
	static char C[][];
	static int DP[][];
	static int mAns = Integer.MAX_VALUE;
	
	public static void main(String[] args) {
		readMap();
		
		boolean find = false;
		for(int i=0; i<H; i++) {
			for(int j=0; j<W; j++) {
				if(C[i][j] == '.') {
					replaceCavity(j, i, '+');
					find=true;
					break;
				}
			}
			if(find) break;
		}
		
		for(int i=0; i<H; i++) {
			for(int j=0; j<W; j++) {
				if(C[i][j] == '.') {
					solve(j, i);
				}
			}
		}
		System.out.println(mAns-1);
	}
		
	static void solve(int startX, int startY) {
		
		Queue<Node> q = new LinkedList<Node>();
		
		Node start = new Node(startX, startY, 0, C);
		q.add(start);
		
		while(!q.isEmpty()) {
			
			Node node = q.poll();
						
			if(DP[node.mY][node.mX] <= node.mStep) continue;
			DP[node.mY][node.mX] = node.mStep;
			
			if(mAns <= node.mStep) continue;
			if(node.mX == 0 || node.mX == W-1) continue;
			if(node.mY == 0 || node.mY == H-1) continue;
			
			if(node.mMap[node.mY][node.mX] == '+') {
				mAns = Math.min(mAns, node.mStep);
				continue;
			}
			
			node.mMap[node.mY][node.mX] = '.';
			
			int nextStep = node.mStep+1;
			int nextX, nextY;
			char nextMap[][] = node.mMap;
			
			//上
			nextX = node.mX;
			nextY = node.mY-1;
			if(node.mMap[nextY][nextX] != '.') {
				Node next = new Node(nextX, nextY, nextStep, nextMap);
				q.add(next);
			}
			//右
			nextX = node.mX+1;
			nextY = node.mY;
			if(node.mMap[nextY][nextX] != '.') {
				Node next = new Node(nextX, nextY, nextStep, nextMap);
				q.add(next);
			}
			//下
			nextX = node.mX;
			nextY = node.mY+1;
			if(node.mMap[nextY][nextX] != '.') {
				Node next = new Node(nextX, nextY, nextStep, nextMap);
				q.add(next);
			}
			//左
			nextX = node.mX-1;
			nextY = node.mY;
			if(node.mMap[nextY][nextX] != '.') {
				Node next = new Node(nextX, nextY, nextStep, nextMap);
				q.add(next);
			}
		}
	}
	
	
	static void readMap() {
		Scanner sc = new Scanner(System.in);
		W = sc.nextInt();
		H = sc.nextInt();
		C = new char[H][W];
		DP = new int[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);
				DP[i][j] = Integer.MAX_VALUE;
			}
		}
	}
	
	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);
	}	
}

class Node {
	int mX, mY, mStep;
	char mMap[][];
	
	Node(int x, int y, int step, char[][] map) {
		mX = x; mY = y; mStep = step;
		mMap = new char[Main.H][Main.W];
		
		for(int i=0; i<Main.H; i++) {
			mMap[i] = map[i].clone();
		}
	}
}