#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  char a[h + 2][w + 2];
  for (int i = 0; i <= h + 1; i++)
    for (int j = 0; j <= w + 1; j++) {
      a[i][j] = '.';
    }
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      cin >> a[i][j];
    }
  for (int i = 1; i <= h; i++)
    for (int j = 1; j <= w; j++) {
      if (a[i][j] == '#' && a[i - 1][j] != '#' && a[i + 1][j] != '#' &&
          a[i][j - 1] != '#' & a[i][j + 1] != '#') {
        cout << "Yes";
        return 0;
      }
    }
  cout << "Yes";
  return 0;
}
