CountingRooms.cpp

//Counting Rooms - https://cses.fi/problemset/task/1192

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int MOD = 1e9 + 7;
const ll INF = 1e18;


const vector<pair<int, int>> DIRECTIONS = {{0, 1}, {1, 0}, {-1, 0}, {0, -1}};


void solve() {
    int n, m;
    cin >> n >> m;
    vector<string> grid(n);
    for (int i = 0; i < n; i++) {
        cin >> grid[i];
    }

    auto dfs = [&](auto dfs, int x, int y) -> void {
        grid[x][y] = '#';
        for (auto [dx, dy]: DIRECTIONS) {
            int nx = x + dx;
            int ny = y + dy;
            if (nx >= 0 && nx < n && ny >= 0 && ny < m && grid[nx][ny] == '.') {
                dfs(dfs, nx, ny);
            }
        }
    };

    int ans = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (grid[i][j] == '.') {
                ans++;
                dfs(dfs, i, j);
            }
        }
    }
    cout << ans << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
//    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}