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