#include <bits/stdc++.h>
using namespace std;
void solve() {
  int h, w;
  cin >> h >> w;
  string board[60];
  for (int i = 0; i < (int)(h); i++) cin >> board[i];
  int dx[] = {1, 0, -1, 0};
  int dy[] = {0, 1, 0, -1};
  bool f = 0;
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(w); j++) {
      if (board[i][j] == '#') {
        int cnt = 0;
        for (int k = 0; k < (int)(4); k++) {
          int x = i + dx[k];
          int y = j + dy[k];
          if (x >= 0 && x < h && y >= 0 && y < w && board[x][y] == '#')
            f = 1;
          else
            cnt++;
        }
        if (cnt == 4) {
          f = 0;
          break;
        }
      }
    }
    if (!f) break;
  }
  if (h == 1 && w == 1 && board[0][0] == '#') {
    cout << "Yes" << endl;
    return;
  }
  cout << (f ? "Yes" : "No") << endl;
}
int main() {
  cout << std::fixed << std::setprecision(10);
  ios::sync_with_stdio(false);
  cin.tie(0);
  solve();
}
