#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  char S[55][55];
  string s;
  for (int i = 1; i <= H; i++) {
    cin >> s;
    for (int j = 1; j <= W; j++) {
      S[i][j] = s[j - 1] == '#';
    }
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (S[i][j] == '#' and S[i][j + 1] != '#' and S[i][j - 1] != '#' and
          S[i + 1][j] != '#' and S[i - 1][j] != '#') {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
  return 0;
}
