#include <bits/stdc++.h>
using namespace std;
int h, w;
long long a, b, c, k;
vector<vector<char>> v;
int main(int argc, char const *argv[]) {
  char c;
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    vector<char> vv;
    for (int j = 0; j < w; j++) {
      cin >> c;
      vv.push_back(c);
    }
    v.push_back(vv);
  }
  bool ok = false;
  bool no = true;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (v[i][j] == '#') no = false;
      if (v[i][j] == '.') continue;
      if (i > 0 && v[i - 1][j] == '#') ok = true;
      if (j > 0 && v[i][j - 1] == '#') ok = true;
      if (i < h - 1 && v[i + 1][j] == '#') ok = true;
      if (j < w - 1 && v[i][j + 1] == '#') ok = true;
    }
  }
  if (no || ok) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
  return 0;
}
