#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  int h, w;
  cin >> h >> w;
  char s[w + 2][h + 2];
  fill(s[0], s[h + 2], '.');
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) cin >> s[j][i];
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      if (s[j][i] == '#' && s[j - 1][i] != '#' && s[j + 1][i] != '#' &&
          s[j][i - 1] != '#' && s[j][i + 1] != '#') {
        cout << fixed << "No" << endl;
        return 0;
      }
    }
  cout << fixed << "Yes" << endl;
}
