#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  int num = 0;
  string board[50];
  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][j - 1] != '#' &&
          board[i - 1][j] != '#' && board[i][j + 1] != '#' &&
          board[i + 1][j] != '#')
        num++;
    }
  }
  if (num == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
