#include <bits/stdc++.h>
using namespace std;
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char>> v(h + 2, vector<char>(w + 2, '.'));
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; j++) {
      cin >> v.at(i).at(j);
    }
  }
  bool ok = false;
  for (int i = 1; i < h + 1; i++) {
    for (int j = 1; j < w + 1; j++) {
      if (v.at(i).at(j) == '.') {
        ok = true;
        continue;
      }
      if (v.at(i - 1).at(j) == '#') {
        ok = true;
        continue;
      } else if (v.at(i + 1).at(j) == '#') {
        ok = true;
        continue;
      } else if (v.at(i).at(j - 1) == '#') {
        ok = true;
        continue;
      } else if (v.at(i).at(j + 1) == '#') {
        ok = true;
        continue;
      } else {
        ok = false;
      }
    }
  }
  if (ok) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
