#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  bool ans = true;
  int n, m;
  cin >> h >> w;
  string s[h + 2][w + 2];
  string t[h];
  for (n = 0; n < h + 2; n++) {
    for (m = 0; m < w + 2; m++) {
      s[n][m] = ".";
    }
  }
  for (n = 0; n < h; n++) {
    cin >> t[n];
  }
  for (n = 1; n < h + 1; n++) {
    for (m = 1; m < w + 1; m++) {
      s[n][m] = t[n - 1].substr(m, 1);
    }
  }
  for (n = 1; n < h + 1; n++) {
    for (m = 1; m < w + 1; m++) {
      if (s[n][m] == "#" && s[n - 1][m] == "." && s[n][m - 1] == "." &&
          s[n + 1][m] == "." && s[n][m + 1] == ".") {
        ans = false;
      }
    }
  }
  if (ans || (h == 1 && w == 1)) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
