#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  vector<vector<int> > vv(n, vector<int>(m)), flag(n, vector<int>(m));
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      char x;
      cin >> x;
      if (x == '#') vv[i][j] = 1;
    }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      if (!vv[i][j]) continue;
      if (i - 1 > 0 && vv[i - 1][j] == 1) flag[i][j] = 1;
      if (i + 1 < n && vv[i + 1][j] == 1) flag[i][j] = 1;
      if (j - 1 > 0 && vv[i][j - 1] == 1) flag[i][j] = 1;
      if (j + 1 < m && vv[i][j + 1] == 1) flag[i][j] = 1;
    }
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++)
      if (vv[i][j] == 1 && !flag[i][j]) return cout << "No", 0;
  cout << "Yes";
}
