#include <bits/stdc++.h>
using namespace std;
int main() {
  int r, s;
  cin >> r >> s;
  vector<string> vec(r);
  for (int i = 0; i < r; i++) {
    cin >> vec.at(i);
  }
  string x, y;
  int count = 0;
  for (int i = 0; i < r; i++) {
    x = vec.at(i);
    for (int j = 0; j < s; j++) {
      if (x.at(j) == '#') {
        if (i != 0) {
          y = vec.at(i - 1);
          if (y.at(j) == '#') {
            count++;
          }
        }
        if (i != r - 1) {
          y = vec.at(i + 1);
          if (y.at(j) == '#') {
            count++;
          }
        }
        if (j != 0) {
          if (x.at(j - 1) == '#') {
            count++;
          }
        }
        if (j != s - 1) {
          if (x.at(j + 1) == '#') {
            count++;
          }
        }
        if (count == 0) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
}
