#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
double pi = 3.1415926535;
int main() {
  int n, m;
  cin >> n >> m;
  char c[n][m];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) cin >> c[i][j];
  bool f = false;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (c[i][j] == '#') {
        if (i > 0 && c[i - 1][j] == '#') f = true;
        if (i < n - 1 && c[i + 1][j] == '#') f = true;
        if (j > 0 && c[i][j - 1] == '#') f = true;
        if (j < m - 1 && c[i][j + 1] == '#') f = true;
        if (f == false) {
          cout << "No" << endl;
          return 0;
        }
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
