#include <bits/stdc++.h>
using namespace std;
const int inf = 1 << 30;
int main() {
  int H, W;
  bool canvas[60][60], ans = true;
  cin >> H >> W;
  char tmp;
  memset(canvas, false, sizeof(canvas));
  for (int h = 1; h <= H; h++) {
    for (int w = 1; w <= W; w++) {
      cin >> tmp;
      if (tmp == '#') canvas[h][w] = true;
    }
  }
  for (int h = 1; h <= H; h++) {
    for (int w = 1; w <= W; w++) {
      if (canvas[h][w])
        if ((!canvas[h][w - 1] && !canvas[h][w + 1]) &&
            (!canvas[h + 1][w] && !canvas[h - 1][w])) {
          ans = false;
        }
    }
  }
  if (ans)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
