#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  string board[51];
  for (int i = 0; i < (h); i++) cin >> board[i];
  for (int i = 0; i < (h); i++) {
    for (int j = 0; j < (w); j++) {
      if (board[i][j] == '#' && board[i - 1][j] != '#', board[i + 1][j] != '#',
          board[i][j - 1] != '#', board[i + 1][j] != '#') {
        cout << "No" << endl;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
