#include <bits/stdc++.h>
using namespace std;
int h, w;
char str[55][55];
int main() {
  cin >> h >> w;
  for (int i = 1; i <= h; i++) {
    gets(str[i]);
    getchar();
  }
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      if (str[i][j] == '#' && str[i][j] != str[i][j - 1] &&
          str[i][j] != str[i][j + 1] && str[i][j] != str[i - 1][j] &&
          str[i][j] != str[i + 1][j]) {
        cout << "No" << endl;
        return 0;
      }
    }
  cout << "Yes" << endl;
  return 0;
}
