#include <bits/stdc++.h>
using namespace std;
const int N = 56;
string a[N];
int n, m;
void work(void) {
  int i, j, f;
  for (i = 0; i < n; i++)
    for (j = 0; j < m; j++)
      if (a[i][j] == '#') {
        f = 0;
        if (i > 0 && a[i - 1][j] == '#')
          f = 1;
        else if (j > 0 && a[i][j - 1] == '#')
          f = 1;
        else if (i <= n - 2 && a[i + 1][j] == '#')
          f = 1;
        else if (j <= m - 2 && a[i][j + 1] == '#')
          f = 1;
        if (f == 0) break;
      }
  if (f == 1)
    cout << "Yes";
  else
    cout << "No";
}
int main(void) {
  int i;
  cin >> n >> m;
  for (i = 0; i <= n; i++) cin >> a[i];
  work();
  return 0;
}
