#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char>> A(h + 2, vector<char>(w + 2));
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> A.at(i).at(j);
    }
  }
  bool can = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (A.at(i).at(j) == '#') {
        if (A.at(i).at(j + 1) == '#' && j + 1 <= w - 1) {
          break;
        } else if (A.at(i - 1).at(j) == '#' && i - 1 >= 0) {
          break;
        } else if (A.at(i).at(j - 1) == '#' && j - 1 >= 0) {
          break;
        } else if (A.at(i + 1).at(j) == '#' && i + 1 <= h - 1) {
          break;
        } else {
          can == false;
          break;
        }
      }
    }
    if (can == false) {
      break;
    }
  }
  if (can) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
