#include <bits/stdc++.h>
using namespace std;
int main() {
  int H, W;
  cin >> H >> W;
  vector<string> S(H + 2);
  for (int i = 1; i <= H; ++i) {
    cin >> S[i];
    S[i] = "." + S[i] + ".";
  }
  S[0] = string(W + 2, '.');
  S[H + 1] = string(W + 2, '.');
  bool flag = true;
  for (int i = 1; i <= H; ++i) {
    for (int j = 1; j <= W; ++j) {
      if (S[i][j] == '.') break;
      if (S[i - 1][j] == '.' && S[i][j - 1] == '.' && S[i][j + 1] == '.' &&
          S[i + 1][j] == '.') {
        flag = false;
      }
    }
  }
  if (flag)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
