#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  char c[53][53];
  for (int i = 1; i <= n; ++i)
    for (int j = 1; j <= m; ++j) cin >> c[i][j];
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= m; ++j) {
      if (c[i][j] == '#' && c[i][j - 1] != '#' && c[i - 1][j] != '#' &&
          c[i][j + 1] != '#' && c[i + 1][j] != '#') {
        cout << "No" << endl;
        return 1;
      }
    }
  }
  cout << "Yes" << endl;
}
