#include <bits/stdc++.h>
using namespace std;
string s;
vector<vector<char>> v;
void solve() {
  int H, W;
  int cnt = 0;
  cin >> H >> W;
  for (int j = 1; j <= W; j++) {
    for (int i = 1; i <= H; i++) {
      cin >> v[j][i];
    }
  }
  for (int j = 1; j <= W; j++) {
    for (int i = 1; i <= H; i++) {
      if (v[j][i] == '#' && v[j - 1][i] != '#' && v[j][i - 1] != '#' &&
          v[j][i + 1] != '#' && v[j + 1][i] != '#')
        cnt++;
    }
  }
  if (cnt == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
int main() {
  solve();
  return 0;
}
