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