#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  string a[30000];
  for (int i = 0; i < H * W; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < H * W; i++) {
    if (a[i] == "#") {
      if (i - 1 % W != 0) {
        if (a[i + 1] != "#" && a[i - 1] != "#" && a[i + W] != "#" &&
            a[i - W] != "#") {
          cout << "No" << endl;
          goto E1;
        }
      } else {
        if (a[i + 1] != "#" && a[i + W] != "#" && a[i - W] != "#") {
          cout << "No" << endl;
          goto E1;
        }
      }
    }
  }
  cout << "Yes" << endl;
E1:
  return 0;
}
