using namespace std;

int main() {
  int h, w;
  cin >> h >> w;
  
  char s[55][55];
  bool can[55][55];
  for(int i = 1; i <= h; i++) {
    for(int j = 1; j <= w; j++) {
      cin >> s[i][j];
      if(s[i][j] == '#') {
        can[i][j] = true;
      }
    }
  }
  
  
  
   bool check = false;
  for(int i = 1; i <= h; i++) {
    for(int j = 1; j <= w; j++) {
      if(can[i][j]) {
        if(!can[i+1][j] && !can[i-1][j] && !can[i][j-1] && !can[i][j+1]) {
          check = true;
          break;
        }
      }
    }
    if(check) break;
  }
  if(!check) cout << "Yes" << endl;
  else cout << "No" << endl;   
}