#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string s[55][55];
  bool can[55][55] = {{true}};
  bool can2 = true;
  cin >> h >> w;
  for (int i = 1; i <= w; i++) {
    for (int j = 1; j <= h; j++) {
      cin >> s[j][i];
      if (s[j][i] == "#") {
        can[j][i] = false;
      }
    }
  }
  for (int i = 1; i <= w; i++) {
    for (int j = 1; j <= h; j++) {
      if (can[i][j] == false) {
        if (!can[i + 1][j] || !can[i - 1][j] || !can[i][j + 1] ||
            !can[i][j - 1]) {
          can2 = false;
          break;
        }
      }
    }
    if (!can2) break;
  }
  if (can2)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
