#include <bits/stdc++.h>
using namespace std;
int dx[] = {-1, 0, 1, 0};
int dy[] = {0, 1, 0, -1};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < (h); ++i) cin >> s[i];
  auto chk = [&](int x, int y) {
    int cnt = 0;
    for (int k = 0; k < (4); ++k) {
      int xx = x + dx[k];
      int yy = y + dy[k];
      if (xx < 0 || xx >= h || yy < 0 || yy >= w) continue;
      if (s[xx][yy] == '#') cnt++;
    }
    if (cnt >= 1) return true;
    return false;
  };
  bool ok = true;
  for (int i = 0; i < (h); ++i)
    for (int j = 0; j < (h); ++j) {
      ok &= chk(i, j);
    }
  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}
