#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string *s;
  cin >> h >> w;
  s = new string[(h + 2) * (w + 2)]();
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) cin >> s[i][j];
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++)
      if (s[i][j] == '#' && s[i + 1][j] != '#' && s[i - 1][j] != '#' &&
          s[i][j + 1] != '#' && s[i][j - 1] != '#') {
        cout << "No\n";
        return 0;
      }
  cout << "Yes\n";
}
