#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char>> s(h, vector<char>(w));
  bool hantei = false;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      hantei = false;
      if (s[i][j] == '#') {
        if (i != h - 1 && s[i + 1][j] == '#') {
          hantei = true;
          break;
        } else if (j != w - 1 && s[i][j + 1] == '#') {
          hantei = true;
          break;
        } else if (i != 0 && s[i - 1][j] == '#') {
          hantei = true;
          break;
        } else if (j != 0 && s[i][j - 1] == '#') {
          hantei = true;
          break;
        }
      }
    }
  }
  if (hantei == true) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
