#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int H, W;
  int n;
  vector<string> canvas;
  const int dx[4] = {-1, 0, 1, 0};
  const int dy[4] = {0, -1, 0, 1};
  bool flag = true;
  cin >> H >> W;
  canvas.resize(H);
  for (int i = 0; i < H; i++) cin >> canvas[i];
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (canvas[i][j] == '.') continue;
      flag = false;
      for (int k = 0; k < 4; k++) {
        int x = i + dx[k];
        int y = j + dy[k];
        if (x < 0 || W <= x) continue;
        if (y < 0 || H <= y) continue;
        flag = flag || (canvas[x][y] == '#');
      }
      if (!flag) break;
    }
    if (!flag) break;
  }
  cout << (flag ? "Yes" : "No") << endl;
  return 0;
}
