#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (size_t i = 0; i < h; i++) {
    cin >> s[i];
  }
  vector<int> xh = {-1, 0, 0, 1};
  vector<int> xw = {0, -1, 1, 0};
  for (size_t i = 0; i < h; i++) {
    for (size_t j = 0; j < w; j++) {
      if (s[i][j] == '#') {
        bool isOK = false;
        for (size_t k = 0; k < 4; k++) {
          int hind = i + xh[k];
          int wind = j + xw[k];
          if (hind >= 0 && hind <= w - 1 && wind >= 0 && wind <= h - 1 &&
              s[hind][wind] == '#') {
            isOK = true;
            break;
          }
        }
        if (!isOK) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
