#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<int>> S(H + 2, vector<int>(W + 2));
  for (int i = 1; i <= H; i++) {
    string s;
    cin >> s;
    for (int j = 1; j <= W; j++) {
      if (s[j] == '#') S[i][j] = 1;
    }
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (S[i][j] and !S[i - 1][j] and !S[i][j - 1] and !S[i + 1][j] and
          !S[i][j + 1]) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
