#include <bits/stdc++.h>
using namespace std;
string s[55][55];
int main() {
  int n, m, cnt = 0;
  cin >> n >> m;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      cin >> s[i][j];
      if (s[i][j] == "#") {
        if (s[i - 1][j] == "#" || s[i + 1][j] == "#" || s[i][j - 1] == "#" ||
            s[i][j + 1] == "#")
          s[i][j] = '.';
        else
          cout << "No" << endl;
      }
      if (s[i][j] == ".") {
        cnt++;
        if (cnt == n * m) cout << "Yes" << endl;
      }
    }
  system("pause");
  return 0;
}
