#include <iostream>
#include <vector>
#include <deque>
#include <tuple>

const std::vector<int> dx{-1, 1, 0, 0}, dy{0, 0, -1, 1};

template <class T>
std::vector<T> vec(int len, T elem) { return std::vector<T>(len, elem); }

constexpr int INF = 1 << 30;

void solve() {
    int w, h;
    std::cin >> w >> h;

    std::vector<std::string> ss(h);
    for (auto& s : ss) std::cin >> s;

    int sx, sy;
    for (sx = 0; sx < h; ++sx) {
        for (sy = 0; sy < w; ++sy) {
            if (ss[sx][sy] == '.') break;
        }
        if (sy < w) break;
    }

    std::deque<std::pair<int, int>> que;
    que.emplace_back(sx, sy);

    auto visited = vec(h, vec(w, false));
    auto dist = vec(h, vec(w, INF));
    dist[sx][sy] = 0;

    while (!que.empty()) {
        int x, y;
        std::tie(x, y) = que.front();
        que.pop_front();

        if (visited[x][y]) continue;
        visited[x][y] = true;

        for (int i = 0; i < 4; ++i) {
            int nx = x + dx[i],
                ny = y + dy[i];

            if (nx < 0 || h <= nx ||
                ny < 0 || w <= ny) continue;

            int nd = dist[x][y] + (ss[nx][ny] == '#');
            if (nd >= dist[nx][ny]) continue;

            dist[nx][ny] = nd;
            if (ss[nx][ny] == '#') {
                que.emplace_back(nx, ny);
            } else {
                que.emplace_front(nx, ny);
            }
        }
    }

    int ans = INF;
    for (int x = 0; x < h; ++x) {
        for (int y = 0; y < w; ++y) {
            if (ss[x][y] != '.' || dist[x][y] == 0) continue;
            ans = std::min(ans, dist[x][y]);
        }
    }

    std::cout << ans << std::endl;
}

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

    solve();

    return 0;
}