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