#include <bits/stdc++.h>
using ll = long long;
using namespace std;
int main() {
  int h, w, dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < (int)(h); i++) {
    cin >> s.at(i);
  }
  for (int i = 0; i < (int)(h); i++) {
    for (int j = 0; j < (int)(h); j++) {
      if (s.at(i)[j] == '.') continue;
      bool flag = false;
      for (int k = 0; k < (int)(4); k++) {
        int nx = j + dx[k], ny = i + dy[k];
        if (nx < 0 || w <= nx || ny < 0 || h <= ny) continue;
        if (s.at(ny)[nx] == '#') flag = true;
      }
      if (flag == false) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
