#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  string board[50];
  cin >> h >> w;
  for (int i = 0; i < h; i++) cin >> board[i];
  int dx[4] = {-1, 0, 0, 1};
  int dy[4] = {0, -1, 1, 0};
  bool can = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (board[i][j] == '.') continue;
      bool canij = false;
      for (int k = 0; k < 4; k++) {
        int ni = i + dy[k];
        int nj = j + dx[k];
        if (ni < 0 || ni > h || nj < 0 || nj > w) continue;
        if (board[ni][nj] == '#') {
          canij = true;
          break;
        }
      }
      if (!canij) {
        can = false;
        break;
      }
    }
  }
  if (can) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
