#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const long long INF = 1LL << 60;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> S(H);
  for (int i = 0; i < H; i++) cin >> S[i];
  for (int i = 0; i < H; i++) {
    bool flg = false;
    for (int j = 0; j < W; j++) {
      if (S[i][j] == '#') {
        if (i + 1 < H && S[i + 1][j] == '#') {
          flg = true;
        } else if (i - 1 >= 0 && S[i - 1][j] == '#') {
          flg = true;
        } else if (j + 1 < W && S[i][j + 1] == '#') {
          flg = true;
        } else if (j - 1 >= 0 && S[i][j - 1] == '#') {
          flg = true;
        }
      } else
        flg = true;
      if (flg == false) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
