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