#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> board(H);
  for (int i = 0; i < H; i++) {
    cin >> board.at(i);
  }
  bool can = true;
  const vector<int> dx = {1, 0, 0, -1};
  const vector<int> dy = {0, 1, -1, 0};
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      bool can2 = false;
      if (board.at(i).at(j) == '#') {
        for (int d = 0; d < 4; d++) {
          const int ni = i + dx.at(d);
          const int nj = j + dy.at(d);
          if (ni >= 0 && ni < H && nj >= 0 && nj < W &&
              board.at(ni).at(nj) == '#') {
            can2 = true;
          }
        }
        can = can2;
      }
    }
  }
  if (can) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
