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