#include <bits/stdc++.h>
using namespace std;
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++) {
    for (int j = 0; j < W; j++) {
      if (s[i][j] == '#') {
        if ((s[i + 1][j] == '#') || (s[i - 1][j] == '#') ||
            (s[i][j + 1] == '#') || (s[i][j - 1] == '#')) {
        } else {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
