#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int h, w;
  cin >> h >> w;
  string s[h + 1];
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; j++) cin >> s[i][j];
  }
  bool flg = false;
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; j++) {
      if (s[i][j] == '#' && s[i - 1][j] != '#' && s[i + 1][j] != '#' &&
          s[i][j - 1] != '#' && s[i][j + 1] != '#')
        flg = true;
    }
  }
  if (flg)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
