#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> map(h);
  for (string &s : map) {
    cin >> s;
  }
  vector<int> dx{1, 0, -1, 0};
  vector<int> dy{0, -1, 0, 1};
  bool ok;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (map.at(i).at(j) == '#') {
        ok = false;
        for (int k = 0; k < 4; k++) {
          if (i + dy.at(k) < 0 || i + dy.at(k) > h - 1 || j + dx.at(k) < 0 ||
              j + dx.at(k) > w - 1) {
            continue;
          }
          if (map.at(i + dy.at(k)).at(j + dx.at(k)) == '#') {
            ok = true;
            break;
          }
        }
      }
    }
    if (!ok) {
      break;
    }
  }
  if (ok) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
