#include <bits/stdc++.h>
using namespace std;
int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, 1, 0, -1};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> ss(h);
  for (int i = 0; i < h; i++) {
    cin >> ss[i];
  }
  bool check = false;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      check = false;
      if (ss[i][j] == '#') {
        for (int k = 0; k < 4; k++) {
          int nextx = i + dx[k];
          int nexty = j + dy[k];
          if (nextx >= 0 && nextx < w && nexty >= 0 && nexty < h) {
            if (ss[nextx][nexty] == '#') check = true;
          }
        }
        if (!check) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
