#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string s[h + 2];
  for (int i = 1; i <= h; ++i) {
    string tmp;
    cin >> tmp;
    s[i].push_back('.');
    s[i].append(tmp);
    s[i].push_back('.');
  }
  for (int i = 0; i < w + 2; ++i) {
    s[0].push_back('.');
    s[h + 1].push_back('.');
  }
  for (int i = 1; i <= h; ++i) {
    for (int j = 1; j <= w; ++j) {
      if (s[i - 1][j] == '.' && s[i + 1][j] == '.' && s[i][j - 1] == '.' &&
          s[i][j + 1] == '.') {
        cout << ("No") << "\n";
        return 0;
      }
    }
  }
  cout << ("Yes") << "\n";
}
