#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  char s[50][50];
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  bool ans = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '.') break;
      int count = 0;
      if (j != 0 && s[i][j - 1] == '#') count++;
      if (i != 0 && s[i - 1][j] == '#') count++;
      if (j != w - 1 && s[i][j + 1] == '#') count++;
      if (i != h - 1 && s[i + 1][j] == '#') count++;
      if (count == 0) ans = false;
      if (!ans) break;
    }
    if (!ans) break;
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
