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