#include <iostream>
#include <vector>
#include <fstream>
#include <queue>
using namespace std;
typedef long long ll;
const int INF = 2e9;
const int di[4] = {-1, 1, 0, 0};
const int dj[4] = {0, 0, -1, 1};
int count_rooms(vector<vector<char>> & mat, int n, int m) {
    vector<vector<bool>> visited(n, vector<bool>(m, false));

    int res = 0;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            if(mat[i][j] == '.' and !visited[i][j]) {
                res++;
                queue<int> q;
                q.push(i);
                q.push(j);

                while(!q.empty()) {
                    int ci = q.front();
                    q.pop();
                    int cj = q.front();
                    q.pop();

                    for(int k = 0; k < 4; k++) {
                        int ti = ci + di[k];
                        int tj = cj + dj[k];

                        if(ti >= 0 and ti < n and tj >= 0 and tj < m and !visited[ti][tj]) {
                            q.push(ti);
                            q.push(tj);
                            visited[ti][tj] = true;
                        }
                    }
                }
            }
        }
    }

    return res;

}
int main() {
    ios_base::sync_with_stdio(false);
    ifstream cin("in.txt");
    int n, m;
    cin >> n >> m;
    vector<vector<char>> mat(n, vector<char>(m));

    for(int i = 0; i < n; i++) {
        for(int j = 0; j < m; j++) {
            cin >> mat[i][j];
        }
    }

    int res = INF;
    for(int row = 0; row < n; row++) {
        vector<vector<char>> tmp(n - 1);
        int ci = 0;
        for(int i = 0; i < n; i++) {
            if(row != i) {
                for(int j = 0; j < m; j++) {
                    tmp[ci].push_back(mat[i][j]);
                }
                ci++;
            }
        }
        res = min(res, count_rooms(tmp, n - 1, m));
    }

    for(int col = 0; col < m; col++) {
        vector<vector<char>> tmp(n);
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < m; j++) {
                if(j != col) {
                    tmp[i].push_back(mat[i][j]);
                }
            }
        }
        res = min(res, count_rooms(tmp, n, m - 1));
    }
    cout << res << endl;

    return 0;
}