#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w, ans;
  cin >> h >> w;
  char c[55][55];
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      cin >> c[i][j];
    }
  }
  for (int i = 1; i <= h; i++) {
    for (int j = 1; j <= w; j++) {
      if (c[i][j] == '#' && c[i + 1][j] == '#' && c[i][j + 1] == '#' &&
          c[i - 1][j] == '#' && c[i][j - 1] == '#')
        ans++;
    }
  }
  if (ans == 0)
    cout << "No" << endl;
  else
    cout << "Yes" << endl;
  return 0;
}
