#include "bits/stdc++.h"
#include <unordered_set>

#define _CRT_SECURE_NO_WARNINGS

#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)
#define REP2(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define REP3(i, x, n) for(decltype(x) i = (x); i <= (n); i++)
#define RREP(i, n) for (decltype(n) i = (n) - 1; i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

using namespace std;

const int dy[] = { 0, 1, 0, -1 };
const int dx[] = { 1, 0, -1, 0 };

using LL = long long int;
using LD = long double;

const int INF = (1 << 30) - 1;
const LL INF64 = ((LL)1 << 62) - 1;
const double PI = 3.1415926535897932384626433832795;

using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<LL>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vd = vector<double>;
using vs = vector<string>;
using vb = vector<bool>;

//==============================================
int w, h;
vvi M;

queue<pii> S;
queue<pii> Scolor1;

void color(int sy, int sx, int num) {
	queue<pii> que;
	que.push(make_pair(sy, sx));

	if (M[sy][sx] == 0 && num == 1) {
		Scolor1.push(make_pair(sy, sx));
	}

	if (M[sy][sx] != 0) return;
	M[sy][sx] = num;

	while (!que.empty()) {
		const int y = que.front().first;
		const int x = que.front().second;
		que.pop();

		REP(i, 4) {
			int ny = y + dy[i];
			int nx = x + dx[i];

			if (nx < 0 || w <= nx || ny < 0 || h <= ny) continue;
			if (M[ny][nx] == INF) continue;
			if (M[ny][nx] == num) continue;

			M[ny][nx] = num;
			que.push(make_pair(ny, nx));

			if (M[ny][nx] == 1 && num == 1) {
				Scolor1.push(make_pair(ny, nx));
			}
		}
	}
}

int bfs(int sy, int sx, vvi bfsM) {
	queue<pii> que;
	que.push(make_pair(sy, sx));

	bfsM[sy][sx] = 9;
	vvi D(h, vi(w));

	while (!que.empty()) {
		const int y = que.front().first;
		const int x = que.front().second;
		que.pop();

		REP(i, 4) {
			int ny = y + dy[i];
			int nx = x + dx[i];

			if (nx < 0 || w <= nx || ny < 0 || h <= ny) continue;
			if (bfsM[ny][nx] == 9) continue;
			if (bfsM[ny][nx] == 1) continue;

			if (bfsM[ny][nx] == 2) {
				return D[y][x];
			}

			D[ny][nx] = D[y][x] + 1;
			bfsM[ny][nx] = 9;
			que.push(make_pair(ny, nx));
		}
	}
	return INF;
}

void solve() {

	for (int n = 1; !S.empty(); n++) {
		int y = S.front().first;
		int x = S.front().second;
		S.pop();

		if (2 < n) n = 2;
		color(y, x, n);
	}

	int ans = INF;
	while (!Scolor1.empty()) {
		int y = Scolor1.front().first;
		int x = Scolor1.front().second;
		Scolor1.pop();

		ans = min(ans, bfs(y, x, M));
	}

	cout << ans << "\n";
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	cin >> w >> h;

	M.resize(h, vi(w, INF));

	string s;
	REP(i, h) {
		cin >> s;
		REP(j, w) {
			if (s[j] == '.') {
				M[i][j] = 0;
				S.push(make_pair(i, j));
			}
		}
	}

	solve();
	return 0;
}