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