#include <bits/stdc++.h>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);

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

    bool flag = true;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i][j] == '#') continue;
            int degree = 0;
            if (i != 0 && a[i - 1][j] != '#') degree++;
            if (i != n - 1 && a[i + 1][j] != '#') degree++;
            if (j != 0 && a[i][j - 1] != '#') degree++;
            if (j != m - 1 && a[i][j + 1] != '#') degree++;
            if (degree >= 3) {
                cout << "YES\n";
                return 0;
            }
            if (degree == 1) flag = false;
        }
    }

    if (flag) cout << "YES\n";
    else cout << "NO\n";
}