#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vl = vector<ll>;
using vs = vector<string>;
const double pi = 3.14159265358979;
const ll mod = 1000000007;
int main() {
  ll H, W;
  cin >> H >> W;
  vector<vector<char>> g(H, vector<char>(W));
  for (ll i = 0; i < H; i++) {
    for (ll j = 0; j < W; j++) {
      cin >> g[i][j];
    }
  }
  bool f = true;
  for (ll i = 0; i < H; i++) {
    for (ll j = 0; j < W; j++) {
      if (g[i][j] == '#') {
        int k = 0;
        if (i + 1 < H && g[i + 1][j] == '#') k++;
        if (i - 1 > 0 && g[i - 1][j] == '#') k++;
        if (j + 1 < W && g[i][j + 1] == '#') k++;
        if (j - 1 > 0 && g[i][j - 1] == '#') k++;
        if (k == 0) f = false;
      }
    }
  }
  if (f)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
