#include <bits/stdc++.h>
using namespace std;
int h, w, cnt = 0;
char c;
map<pair<int, int>, char> m;
vector<pair<int, int>> v;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> h >> w;
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      cin >> c;
      m[make_pair(i, j)] = c;
      if (c == '#') v.push_back(make_pair(i, j));
    }
  }
  if (v.empty())
    cout << "No";
  else {
    for (int i = 0; i < v.size(); i++) {
      if ((m[make_pair(v[i].first - 1, v[i].second)] != '#') &&
          (m[make_pair(v[i].first + 1, v[i].second)] != '#') &&
          (m[make_pair(v[i].first, v[i].second - 1)] != '#') &&
          (m[make_pair(v[i].first, v[i].second + 1)] != '#')) {
        cnt++;
      }
    }
    if (cnt == 0)
      cout << "Yes";
    else
      cout << "No";
  }
  return 0;
}
