#include <bits/stdc++.h>
using namespace std;
int main() {
  int w, h;
  bool jad;
  cin >> h >> w;
  vector<string> a(h);
  for (int i = 0; i < h; i++) cin >> a.at(i);
  vector<int> dx = {0, 1, 0, -1};
  vector<int> dy = {1, 0, -1, 0};
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (a.at(i).at(j) == '#') {
        jad = true;
        int tmp = 0;
        for (int k = 0; k < 4; k++) {
          int ni = i + dy.at(k);
          int nj = j + dx.at(k);
          if (ni < 0 || ni >= h || nj < 0 || nj >= w) continue;
          if (a.at(ni).at(nj) == '.') {
            tmp++;
          }
          if (tmp == 4) {
            cout << "NO" << endl;
            return 0;
          }
        }
      }
    }
  }
  if (jad == true)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
