#include <bits/stdc++.h>
using namespace std;
const long long INF = 1LL << 60;
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(w);
  for (int i = 1; i <= h; i++) cin >> s[i];
  int count = 0;
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (s[i][j] == '#' && s[i][j - 1] != '#' && s[i - 1][j] != '#' &&
          s[i + 1][j] != '#')
        count++;
    }
  }
  if (count == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
