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