#include <bits/stdc++.h>
using namespace std;
const int maxn = 50;
int h, w;
char s[maxn][maxn];
bool check = true;
int main() {
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> s[i][j];
    }
  }
  for (int i = 0; i < h; i++) {
    for (int j = 0, temp; j < w; j++) {
      if (s[i][j] == '#') {
        temp = 0;
        if (s[i - 1][j] == '#' && i - 1 >= 0) {
          temp++;
        } else if (s[i + 1][j] == '#' && i + 1 < h) {
          temp++;
        } else if (s[i][j + 1] == '#' && j + 1 < w) {
          temp++;
        } else if (s[i][j - 1] == '#' && j - 1 >= 0) {
          temp++;
        }
      }
      if (temp == 0) {
        check = false;
        break;
      }
    }
  }
  if (check) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
