#include <bits/stdc++.h>
using ll = long long;
using namespace std;
const int INF = 1001001001;
int main(void) {
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  for (ll i = (0); i < (H); i++) cin >> s[i];
  int dx[] = {0, 0, -1, 1};
  int dy[] = {1, -1, 0, 0};
  bool ok = true;
  for (ll i = (0); i < (H); i++)
    for (ll j = (0); j < (W); j++) {
      if (s[i][j] == '.') continue;
      bool f = false;
      for (ll k = (0); k < (4); k++) {
        int id = i + dx[k];
        int jd = j + dy[k];
        if (id < 0 || id >= W || jd < 0 || jd >= H) continue;
        if (s[id][jd] == '#') f = true;
      }
      if (!f) ok = false;
    }
  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
