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