#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

int w, h;
string c[22];

int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

const int MAX = 22 * 22;
struct edge {
    int to, cost;
};

vector<edge> G[MAX];
int d[MAX];

void dijkstra(int s) {
    priority_queue<P, vector<P>, greater<P> > que;
    for (int i = 0; i < MAX; i++) d[i] = inf;
    d[s] = 0;
    que.push(P(0, s));
    while (!que.empty()) {
        P p = que.top(); que.pop();
        int v = p.second;
        if (d[v] < p.first) continue;
        for (int i = 0; i < G[v].size(); i++) {
            edge e = G[v][i];
            if (d[e.to] > d[v] + e.cost) {
                d[e.to] = d[v] + e.cost;
                que.push(P(d[e.to], e.to));
            }
        }
    }
}

bool used[22][22];
void dfs(int y, int x) {
    used[y][x] = true;
    for (int k = 0; k < 4; k++) {
        int Y = y + dy[k], X = x + dx[k];
        if (0 <= Y && Y < h && 0 <= X && X < w && !used[Y][X] && c[Y][X] == '.') {
            dfs(Y, X);
        }
    }
}

int solve() {
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            for (int k = 0; k < 4; k++) {
                int y = i + dy[k], x = j + dx[k];
                if (0 <= y && y < h && 0 <= x && x < w) {
                    G[i*w+j].push_back(edge{y*w+x, (c[y][x]=='#'?1:0)});
                }
            }
        }
    }

    int s = -1, t = -1;
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (c[i][j] == '.') {
                s = i * w + j;
                dfs(i, j);
                break;
            }
        }
        if (s >= 0) break;
    }

    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (c[i][j] == '.' && !used[i][j]) {
                t = i * w + j;
                break;
            }
        }
    }

    dijkstra(s);
    return d[t];
}

void input() {
    cin >> w >> h;
    for (int i = 0; i < h; i++) cin >> c[i];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    cout << solve() << endl;
}