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