#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(H + 2, "");
  for (int i = 0; i < (int)(W + 2); i++) {
    s[0] += '.';
    s[H + 1] += '.';
  }
  for (int i = 1; i <= H; ++i) {
    string str;
    cin >> str;
    s[i].append(".");
    s[i].append(str);
    s[i].append(".");
  }
  bool flag = true;
  for (int i = 1; i < W + 1; ++i) {
    for (int j = 1; j < W + 1; ++j) {
      if (s[i][j] == '#' && ((s[i - 1][j] == '.' && s[i + 1][j] == '.') &&
                             (s[i][j + 1] == '.' && s[i][j - 1] == '.')))
        flag = false;
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
