#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char s[h][w];
  bool flag = true;
  for (int i = 0; i < h; i++) {
    cin >> s[h];
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      for (int k = 0; k < 4; k++) {
        if (k == 0 && i != 0 && s[i - 1][j] == '#') {
          flag == true;
          break;
        } else if (k == 1 && i != h - 1 && s[i + 1][j] == '#') {
          flag == true;
          break;
        } else if (k == 2 && j != 0 && s[i][j - 1] == '#') {
          flag == true;
          break;
        } else if (k == 3 && j != w - 1 && s[i][j + 1] == '#') {
          flag == true;
          break;
        } else {
          flag == false;
        }
      }
    }
  }
  if (flag == true) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
