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