#include <bits/stdc++.h>
using namespace std;
const long long int m = pow(10, 9) + 7;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int H, W, cnt = 0;
  cin >> H >> W;
  char c[H][W];
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) cin >> c[i][j];
  }
  for (int i = 1; i <= H; i++) {
    for (int j = 1; j <= W; j++) {
      if (c[i][j] == '#' && c[i][j - 1] != '#' && c[i - 1][j] != '#' &&
          c[i][j + 1] != '#' && c[i + 1][j] != '#')
        cnt++;
    }
  }
  if (cnt == 0)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
