#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char table[55][55];
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> table[h][w];
    }
  }
  int count = 0;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (table[i][j] == '#' and table[i - 1][j] != '#' and
          table[i][j + 1] != '#' and table[i + 1][j] != '#' and
          table[i][j - 1] != '#')
        count++;
    }
  }
  cout << (count ? "No" : "Yes") << endl;
}
