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