#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char ch[52][52];
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) cin >> ch[i][j];
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (ch[i][j - 1] == '.' && ch[i][j + 1] == '.' && ch[i + 1][j] == '.' &&
          ch[i - 1][j] == '.') {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
