#include <bits/stdc++.h>
using namespace std;
char ch[52][52];
int main() {
  int h, w;
  memset(ch, '.', sizeof(ch));
  cin >> h >> w;
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) cin >> ch[i][j];
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++)
      if ((ch[i - 1][j] == '#' || ch[i][j - 1] == '#' || ch[i + 1][j] == '#' ||
           ch[i][j + 1] == '#') &&
          ch[i][j] == '#')
        ;
      else {
        cout << "No";
        return 0;
      }
  cout << "Yes";
}
