#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) { return b != 0 ? gcd(b, a % b) : a; }
int lcm(int a, int b) { return a * b / gcd(a, b); }
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < h; i++) {
    cin >> s.at(i);
  }
  bool ans = true;
  int y[4] = {0, 0, -1, 1};
  int x[4] = {1, -1, 0, 0};
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s.at(i).at(j) == '#') {
        int check = 0;
        for (int k = 0; k < 4; k++) {
          int yy = i + y[k];
          int xx = j + x[k];
          if (yy < 0 || yy >= h || xx < 0 || xx >= w) continue;
          if (s.at(yy).at(xx) == '#') check++;
        }
        if (check == 0) ans = false;
        break;
      }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
