#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
const int di[] = {-1, 0, 1, 0};
const int dj[] = {0, 1, -1, 0};
int main() {
  int h, w;
  cin >> h >> w;
  vector<string> s(h);
  for (int i = 0; i < h; i++) cin >> s[i];
  for (int i = 0; i < h; i++) {
    for (int j = 0; j < w; j++) {
      if (s[i][j] == '.') continue;
      bool flag = true;
      for (int dir = 0; dir < 4; dir++) {
        int ni = i + di[dir], nj = j + dj[dir];
        if (ni < 0 || ni >= h || nj < 0 || nj >= w) continue;
        if (s[ni][nj] == '#') flag = false;
      }
      if (flag) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}
