#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
const string alp = "abcdefghijklmnopqrstuvwxyz";
const string ALP = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int main() {
  string s[50];
  int h, w, c;
  cin >> h >> w;
  for (int i = (0); i < (h); ++i) {
    cin >> s[i];
  }
  for (int i = (0); i < (h); ++i) {
    for (int j = (0); j < (w); ++j) {
      c = 0;
      if (i > 0) {
        if (s[i - 1][j] == '#') c++;
      }
      if (i < h) {
        if (s[i + 1][j] == '#') c++;
      }
      if (j > 0) {
        if (s[i][j - 1] == '#') c++;
      }
      if (j < w) {
        if (s[i][j + 1] == '#') c++;
      }
      if (!c) {
        cout << "No";
        return 0;
      }
    }
  }
  cout << "Yes";
  return 0;
}
