#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  cin >> H >> W;
  vector<string> s;
  s.push_back(string(W + 2, '.'));
  for (int i = 0; i < H; i++) {
    string x;
    cin >> x;
    s.push_back("." + x + ".");
  }
  s.push_back(string(W + 2, '.'));
  for (int i = 1; i <= W; i++) {
    for (int j = 1; j <= H; j++) {
      if (s[i][j] == '#' && s[i][j + 1] == '.' && s[i][j - 1] == '.' &&
          s[i + 1][j] == '.' && s[i - 1][j] == '.') {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
