#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W = 0;
  int i, j = 0;
  cin >> H >> W;
  char c[55][55];
  bool hantei;
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      cin >> c[i][j];
    }
  }
  for (i = 1; i <= H; i++) {
    for (j = 1; j <= W; j++) {
      if (c[i][j] == '#') {
        if (c[i][j + 1] == '#' || c[i][j - 1] == '#' || c[i + 1][j] == '#' ||
            c[i - 1][j] == '#') {
          hantei = true;
        } else {
          hantei = false;
        }
      }
    }
  }
  if (hantei == true) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
