#include <bits/stdc++.h>
using namespace std;
int main() {
  bool flag = 1;
  int H, W;
  cin >> H >> W;
  string Pic[H + 2];
  string frame;
  for (int i = 0; i < W + 2; i++) frame += ".";
  Pic[0] = frame;
  Pic[W + 1] = frame;
  for (int i = 1; i <= H; i++) {
    cin >> Pic[i];
    Pic[i] = "." + Pic[i] + ".";
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (Pic[i][j] == '#') {
        if (Pic[i + 1][j] == '#' || Pic[i - 1][j] == '#' ||
            Pic[i][j + 1] == '#' || Pic[i][j - 1] == '#') {
          flag = 1;
        } else {
          flag = 0;
          break;
        }
      }
    }
    if (flag == 0) break;
  }
  if (flag == 1)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
