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