#include <bits/stdc++.h>
using namespace std;
int main() {
  int x, y;
  cin >> x >> y;
  vector<int> dx = {1, 0, -1, 0};
  vector<int> dy = {0, -1, 0, 1};
  vector<string> board(x);
  for (int i = 0; i < (x); i++) cin >> board[i];
  for (int i = 0; i < (x); i++) {
    for (int j = 0; j < (y); j++) {
      for (int k = 0; k < (4); k++) {
        int xx = i + dx[k];
        int yy = j + dy[k];
        int cnt = 0;
        if (0 <= xx && xx < x && 0 <= yy && yy < y && board[i][j] == '#' &&
            board[xx][yy] == '#') {
          cnt++;
        }
        if (!cnt) {
          cout << "No" << '\n';
          return 0;
        }
      }
    }
  }
  cout << "Yes" << '\n';
  return 0;
}
