#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string board[60];
  cin >> h >> w;
  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] == '#') {
        if ((board[i - 1][j] == '.' && i - 1 >= 0) &&
            (board[i + 1][j] == '.' && i + 1 < h) &&
            (board[i][j - 1] == '.' && j - 1 >= 0) &&
            (board[i][j + 1] == '.' && j + 1 < w)) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
