#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vec = vector<ll>;
using Graph = vector<vector<ll>>;
const ll dx[4] = {1, 0, -1, 0};
const ll dy[4] = {0, 1, 0, -1};
int main() {
  cout << fixed << setprecision(16);
  ll h, w;
  cin >> h >> w;
  vector<string> field(h);
  for (ll i = 0; i < h; i++) {
    cin >> field[i];
  }
  bool check = true;
  for (ll i = 0; i < h; i++) {
    for (ll j = 0; j < w; j++) {
      if (field[i][j] == '#') {
        check = false;
        for (ll k = 0; k < 4; k++) {
          ll zi = i + dx[k];
          ll zj = j + dy[k];
          if (zi < 0 || zi >= h || zj < 0 || zj >= w) continue;
          if (field[zi][zj] == '#') check = true;
        }
      }
    }
  }
  if (check)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
