#include <iostream>
#include <queue>
using namespace std;

struct State {
    int row, col, times;
};

const int kMAX_W = 30;
const int kMAX_H = 30;

int W, H;
string C[kMAX_H];
bool used[kMAX_H][kMAX_W];
bool is_start[kMAX_H][kMAX_W];

int dr[4] = {1, 0, -1, 0},
    dc[4] = {0, 1, 0, -1};

// 一つ目の空洞部分を調べる
void DFS(int r, int c, queue<State>& que) {
    used[r][c] = true;
    is_start[r][c] = true;
    que.push((State){r, c, 0});

    for (int i = 0; i < 4; i++) {
        int nr = r + dr[i], nc = c + dc[i];
        if (0 <= nr && nr < H && 0 <= nc && nc < W &&
                !used[nr][nc] && C[nr][nc] == '.') {
            DFS(nr, nc, que);
        }
    }
}

void Solve() {
    queue<State> que;
    for (int r = 0; r < H; r++) {
        bool find_cave = false;
        for (int c = 0; c < W; c++) {
            if (C[r][c] == '.') {
                DFS(r, c, que);
                find_cave = true;
                break;
            }
        }
        if (find_cave) break;
    }

    while (!que.empty()) {
        State s = que.front(); que.pop();
        if (C[s.row][s.col] == '.' && !is_start[s.row][s.col]) {
            cout << s.times << endl;
            return;
        }
        for (int i = 0; i < 4; i++) {
            int nr = s.row + dr[i], nc = s.col + dc[i];
            if (0 <= nr && nr < H && 0 <= nc && nc < W && !used[nr][nc]) {
                int times = s.times + (C[nr][nc] == '#' ? 1 : 0);
                used[nr][nc] = true;
                que.push((State){nr, nc, times});
            }
        }
    }
}

int main() {
    cin >> W >> H;

    for (int i = 0; i < H; i++) {
        cin >> C[i];
    }

    Solve();

    return 0;
}