#include <bits/stdc++.h>
using namespace std;
const long long INF = 1000000000;
const int MOD = 1000000007;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char>> s(h, vector<char>(w));
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      cin >> s[i][j];
    }
  }
  bool f = false;
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (s[i][j] == '.') continue;
      f = false;
      if (i != 0 && s[i - 1][j] == '#') f = true;
      if (i != h - 1 && s[i + 1][j] == '#') f = true;
      if (j != 0 && s[i][j - 1] == '#') f = true;
      if (j != w - 1 && s[i][j + 1] == '#') f = true;
    }
    if (!f) {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
}
