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

#define MAX 1010
using namespace std;

string s[MAX];
vector<vector<int> > g;
vector<int> mt, used;

int dfs(int v) {
    if (used[v]) return 0;
    used[v] = 1;
    for (int i = 0; i < g[v].size(); i++) {
        int to = g[v][i];
        if (mt[to] == -1 || dfs(mt[to])) {
            mt[to] = v;
            return 1;
        }
    }
    return 0;
}

int main() {
    int n, m;
    cin >> n >> m;

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

    g.resize(n * m);

    int kl = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {

            if (s[i][j] == '#') continue;
            kl++;

            if ((i + j) % 2 == 1) continue;

            int u = i * m + j;

            if ((j > 0) && (s[i][j - 1] == '.')){
                g[u].push_back(u - 1);
            }

            if ((j < m - 1) && (s[i][j + 1] == '.')) {
                g[u].push_back(u + 1);
            }

            if ((i > 0) && (s[i - 1][j] == '.')) {
                g[u].push_back(u - m);
            }

            if ((i < n - 1) && (s[i + 1][j] == '.')) {
                g[u].push_back(u + m);
            }
        }
    }

    mt = vector<int>(n * m, -1);
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            if ((i + j) % 2 == 1) continue;
            used = vector<int>(n * m, 0);
            dfs(i*m + j);
        }
    }

    int counter = 0;
    for (int i = 0; i < n * m; i++) {
        if (mt[i] != -1) {
            counter++;
        }
    }

    if (counter * 2 == kl) {
        cout << "Yes";
    } else {
        cout << "No";
    }
}