#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int,int> pint;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
const int INF = 100000000;
const int dx[4]={0,1,0,-1}, dy[4]={-1,0,1,0};
struct P{int x;int y;P(int X=0,int Y=0){x=X;y=Y;}};

int W,H;
char c[22][22];
vector<P> cave1;
vector<P> cave2;

bool sec = false;
void dfs(int x, int y) {
	c[y][x] = '#';
	if(!sec) cave1.push_back(P(x,y));
	else  cave2.push_back(P(x,y));

	rep(i,4) {
		int nx = x + dx[i];
		int ny = y + dy[i];
		if(nx >= 0 && nx < W && ny >= 0 && ny < H) {
			if(c[ny][nx] == '.') dfs(nx, ny);
		}
	}
	return;
}

int main() {
	cin >> W >> H;
	rep(i,H) {
		scanf("%s", c[i]);
	}

	rep(y,H) {
		rep(x,W) {
			if(c[y][x] == '.') {
				dfs(x, y);
				sec = true;
			}
		}
	}

	int ans=INF;
	int siz1 = cave1.size();
	int siz2 = cave2.size();
	rep(i,siz1) {
		rep(j,siz2) {
			ans = min(ans, abs(cave1[i].x - cave2[j].x) + abs(cave1[i].y - cave2[j].y));
		}
	}
	printf("%d\n",ans-1);
	return 0;
}