#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> line(h);
  for (int i = 0; i < h; ++i) {
    cin >> line.at(i);
  }
  const int dx[4] = {0, 1, 0, -1};
  const int dy[4] = {1, 0, -1, 0};
  bool can = 1;
  for (int i = 0; i < h; ++i) {
    if (!can) break;
    for (int j = 0; j < w; ++j) {
      if (line.at(i).at(j) == '.') continue;
      bool flag = 0;
      for (int k = 0; k > 4; ++k) {
        const int x = i + dx[k];
        const int y = j + dy[k];
        if (x < 0 || x >= h) continue;
        if (y < 0 || y >= w) continue;
        if (line.at(x).at(y) == '#') flag = 1;
        if (!flag) {
          can = 0;
          break;
        }
      }
    }
  }
  if (can)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
