#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<char>> A(H + 2, vector<char>(W + 2, '.'));
  for (int i = 1; i <= H; i++) {
    string S;
    cin >> S;
    for (int j = 1; j <= W; j++) {
      A[i][j] = S.at(j - 1);
    }
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (A[i][j] != '#') break;
      if (A[i + 1][j] == '#') break;
      if (A[i - 1][j] == '#') break;
      if (A[i][j + 1] == '#') break;
      if (A[i][j - 1] == '#') break;
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
}
