#include <bits/stdc++.h>
using namespace std;
string s[100];
int x, y;
int main() {
  cin >> x >> y;
  for (int i = 1; i <= x; i++)
    for (int j = 1; j <= y; j++) cin >> s[i][j];
  bool OK = false;
  int YES = 0;
  for (int i = 1; i <= x; i++)
    for (int j = 1; j <= y; j++)
      if (s[i][j] == '#') {
        if (i + 1 <= x) {
          if (s[i + 1][j] == '.')
            YES++;
          else
            YES = -100;
        }
        if (i - 1 >= 1) {
          if (s[i - 1][j] == '.')
            YES++;
          else
            YES = -100;
        }
        if (j + 1 <= y) {
          if (s[i][j + 1] == '.')
            YES++;
          else
            YES = -100;
        }
        if (j - 1 >= 1) {
          if (s[i][j - 1] == '.')
            YES++;
          else
            YES = -100;
        }
        if (YES > 0) OK = true;
        YES = 0;
      }
  if (OK)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
