#include <bits/stdc++.h>
using ll = long long;
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
int main() {
  int h, w;
  cin >> h >> w;
  vector<vector<char>> s(h, vector<char>(w));
  for (ll i = 0; i < h; i++)
    for (ll j = 0; j < w; j++) cin >> s[i][j];
  vector<vector<bool>> out(h, vector<bool>(w, false));
  for (ll i = 0; i < h; i++) {
    for (ll j = 0; j < w - 1; j++) {
      if (!(s[i][j] == '#' && s[i][j + 1] != '#' && s[i][j - 1] != '#' &&
            s[i - 1][j] != '#' && s[i + 1][j] != '#')) {
        cout << "No\n";
        return 0;
      }
    }
  }
  cout << "Yes";
  cout << "\n";
  return 0;
}
