#include <iostream>
#include <vector>
#include <string>
#include <queue>

using namespace std;

const int INF = 1e9;

int main() {
    int H, W;
    cin >> H >> W;
    vector<string> C(H);
    for (int i = 0; i < H; ++i) cin >> C[i];

    vector<vector<int>> dist(H, vector<int>(W, INF));
    priority_queue<pair<int, pair<int, int>>, vector<pair<int, pair<int, int>>>, greater<pair<int, pair<int, int>>>> pq;

    dist[0][0] = 0;
    pq.push({0, {0, 0}});

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

    while (!pq.empty()) {
        int d = pq.top().first;
        int y = pq.top().second.first;
        int x = pq.top().second.second;
        pq.pop();

        if (d > dist[y][x]) continue;

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

            if (ny >= 0 && ny < H && nx >= 0 && nx < W) {
                int cost = 1;
                if (C[ny][nx] == '#' && C[y][x] != '#') cost = 2;

                if (dist[ny][nx] > d + cost) {
                    dist[ny][nx] = d + cost;
                    pq.push({dist[ny][nx], {ny, nx}});
                }
            }
        }
    }

    cout << dist[H - 1][W - 1] << endl;
    return 0;
}